Overview

For most households in Blewbury a car is essential. People living in a town or city are often able to do without a car by using public transport, bicycles and walking. However, it’s more difficult for people living in a village like Blewbury, with limited bus service and few shops and services within walking distance. Cycling, walking and improved bus services can play a role for some journeys, and many households with two or more cars might well be able to manage with one. But for most of us, convenient access to cars will almost certainly be needed for the foreseeable future.

The decision to buy or replace a car is likely to be made for reasons other than the effects on the environment. However, when making a choice of what to buy you should also consider environmental issues. In this section we summarise these.

Should I keep my old car as long as possible?

If you do a high mileage, sell your relatively inefficient car to someone who will do a low mileage, and then buy a more efficient second-hand car the outcome is clearly beneficial.

If you scrap an old, inefficient car and purchase a new car things are more complicated. If you do a low mileage, and the new car is not significantly more efficient, there is a strong environmental argument for waiting. However, if the new car is much more efficient – as many of them are – or if the old car may be expensive to repair, the decision becomes less clear and depends on the circumstances.

It has been estimated that the CO₂ cost of manufacturing a new car and scrapping the old one is perhaps around 10% of the total emissions during the lifetime of the vehicle.

How useful are the official fuel consumption and emission figures?

The official figures for all cars being sold must be provided on manufacturers’ websites and advertising. However, for a more comprehensive listing, including searches for specific models, go to carfueldata.direct.gov.uk.

The combined figure for fuel consumption is the average of the urban and extra-urban (rural) figures. Most people find that the actual consumption they achieve is worse than the official combined figure. Some models get closer to the official figure than others, but what you achieve also depends on the type of driving you do and your driving style – we give some fuel-saving tips here.

CO₂ emissions depend on the fuel consumption, and directly affect the road tax payable – this is shown in the table below. New cars on sale now have emissions labels, as in the picture.

These figures are based on a stationary rolling-road test, and ignore many real-world factors such as motorway driving and aerodynamics. However, accurate testing under reproducible real conditions is not easy, and better measures are not readily available.

* The official figures provide an approximate guide to the relative efficiency of different cars.

Why should I choose a small, light car?

The energy needed to achieve a given performance is greatly affected by the weight of the car. That is why small cars tend to have the best fuel consumption. Weight can also be reduced by using lighter materials such as aluminium or plastic in place of steel, but the lighter material is often more expensive than steel and often takes more energy to produce. The benefits of lighter weight should show up in the official consumption figures.

* For environmental reasons you should choose the lightest vehicle that will meet your needs.

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Choosing between petrol, diesel, hybrid, electric and alternative fuels

Diesel cars typically achieve 30–40% more miles per gallon than petrol ones. The environmental benefit is not quite as big as that because diesel produces more CO₂ per litre, but is still significant. Diesels are more expensive to buy than equivalent petrol-engined cars, and diesel fuel costs a bit more than petrol, but the differences are almost certain to be repaid in lower fuel bills over the life of the car.

Hybrid cars have both petrol and electric engines, and store energy in batteries. Their use of regenerative braking (see below) and the ability to run the main engine at its optimal speed achieves significant improvements in consumption, typically making petrol hybrids rival the emissions of diesels. However, the designs are complex and are more expensive to manufacture and service, so it is less likely that the extra cost will be repaid in reduced fuel bills over the life of the car.

Electric cars suffer because they require heavy batteries. At present it is difficult to provide a viable electric car with a range of more than 100–150 miles, and the required batteries will make them very expensive. They are most beneficial for city use, where the lack of exhaust fumes is a significant advantage. The running cost is much less than for a conventional car, and even at present the CO₂ generated at the power station is less than from a conventional motor – but ideally the electricity used should be generated from renewable, low-carbon sources. However, the 8 hours or more to recharge the battery is a serious disadvantage.

* Because of their cost, charging problems and limited range, it is unlikely that pure electric cars will be a realistic general-purpose option for at least several years.

Alternative fuel cars such as LPG often require modification of a standard car, with the replacement fuel tank taking up space in the boot. Maintenance and servicing can be problematic. They are not currently sensible options for most users, but we describe future options in more detail elsewhere.

* Overall, the first choice on environmental grounds is currently an efficient diesel-engined car.

Energy saving features

A wide variety of technical changes can be used to save fuel. Two of the most significant are:

• Regenerative braking, where energy is stored as the vehicle slows down or goes downhill, and can be released to assist acceleration or hill climbing
• Stop-start systems, where the engine is stopped whenever the car is stationary; this is most effective in cities

Other measures include disconnecting the alternator when not needed, low rolling-resistance tyres, and improved aerodynamics.

* The user need not be much concerned about how higher efficiency is achieved, and can just consider the overall performance figures.

* A stop-start system is advantageous if your journeys involve many traffic lights and/or heavy congestion.

Is an ‘eco’ version of a car a sensible option?

Whether ‘eco’ versions are really better depends on what has been done to improve consumption and emission figures. Some eco models are indeed better, but for others the fuel consumption is only slightly better. There are often sacrifices, such as no air-conditioning, tyres with lower rolling resistance but worse road holding, and sparse equipment to save weight. There is usually a higher price which may or may not be justified.

Some ‘eco’ features are now appearing on otherwise conventional cars, e.g. stop-start systems. And some manufacturers, for example BMW, prefer to introduce improvements to as much as their model range as possible rather than limit them to special ‘eco’ models.

* An ‘eco’ version may be a sensible purchase, but compare specifications with other models carefully.

Automatic or manual gearbox?

Most automatics use a fluid torque converter, which wastes power and so uses more fuel than the equivalent manual model. Recent designs are basically manual gearboxes with electronically controlled clutches, and consumption figures can be similar to manual versions. A good driver of a manual car can achieve better consumption than a driver with an automatic because they can anticipate upcoming conditions, but the discrepancy is sometimes very small.

* Provided the automatic version does not involve a significant penalty in consumption figures, the choice can be a matter of personal taste.

Is it worth waiting for a car still to be launched?

It is likely that there will continue to be improvements in efficiency on all types of car. It is also likely that a much wider range of hybrid options will become available, but the full benefit of a hybrid requires a purpose-built design rather than an adaptation of a conventional model.

Hybrid diesel cars are likely to achieve the best fuel efficiency but will probably be relatively expensive.

There will soon be hybrids with the capability of charging the battery directly from the mains. Some of these will be designed primarily as electric cars, with small petrol or diesel engines to get around their range limitations.

A number of manufacturers will be launching electric cars. One solution to the problem of the cost of large batteries is for the user to hire the battery from the manufacturer. This might eventually lead to the possibility of ‘refilling’ an electric car by quickly exchanging a used battery for a fully charged one.

* It is likely that waiting will allow the purchase of a rather more efficient car, and there will be a wide variety of options for hybrid cars. The other developments are not likely to be attractive for residents in a country village.

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Choosing Between Currently Available Models

Petrol: Why not just choose a small, frugal petrol car?

Petrol-driven cars are the least expensive to buy. Look for overall fuel consumption above, say, 50 miles per gallon. Current designs struggle to do much better than that, although advances in technology such as sophisticated valve control (e.g. Fiat MultiAir) or small engines with supercharging and turbo-charging (e.g. Volkswagen group) promise some improvement. Petrol engines are much more efficient than they used to be, and petrol also emits less pollution than diesel, although new and tougher standards are narrowing the gap.

* If you don’t drive much then a small, efficient petrol car might be a good choice.

Diesel: Is it better than petrol or a hybrid?

Diesel-powered cars have been popular for a long time in countries that have lower taxes on diesel fuel than petrol, such as France and Italy. In the UK diesel costs about the same and sometimes more than petrol (graph), and diesel cars are also more expensive to buy. The recent popularity of diesels, which now have over 50% of the market, is due to much lower fuel consumption (which also leads to lower annual road tax).

Pros

• For similar performance, most diesels are roughly 30–40% better than petrol in terms of consumption, e.g. you might go 130–140 miles when the same amount of petrol would go 100 miles. Thus, many diesel cars can travel more than, say, 600 miles on a tank of fuel. Even some fairly big diesel cars consume the same or less than a small, efficient petrol car if the engine is a modern design. Diesel CO₂ emissions are also lower than petrol over a given distance, but proportionately by not quite as much as the reduction in consumption.
• Many small diesel cars have fuel consumption as good or better than present hybrids, especially for country and motorway driving (which is not part of the official consumption tests). This means that most of the cars currently offering the very lowest consumption tend to be the diesel, manual-gearbox versions of some superminis such as the Ford Fiesta or Volkswagen Polo – especially in their ‘eco’ versions. The best currently emit less than 90 g/km of CO₂; cars emitting less than 100 g/km are exempt from annual road tax. A few of these models also claim over 80 miles per gallon of fuel. Although in most real-world testing they don’t quite achieve this, even 60 or 70-odd miles per gallon is very good at present.
• Modern diesels are quieter and produce less vibration than older ones, and except when idling it is difficult to tell the difference from petrol. The use of turbo-charging means that modern diesels can also have good acceleration.
• Modern diesel engines use particulate filters to meet tougher pollution standards (see cons, below) – look for Euro 5 rather then the older Euro 4 compliance – as well as using other high-tech methods to minimise pollution and use fuel efficiently.
• As fuel prices rise, diesels have become more popular, and the higher initial price can be at least partly offset by higher resale value.

Cons

• Diesel fuel tends to cost a bit more than petrol in the UK (the difference varies), and the cars themselves are typically around £1000 more expensive. In strict financial terms you need to drive a lot for diesel to pay off the extra capital cost.
• Older diesel engine designs emit soot. Soot contributes to global warming and pollution, and is bad for health, including possibly causing cancer.
• Although the gap is narrowing, diesels emit more nitrogen oxides.
• New, cleaner diesel engines are complex and high-tech, so repairs could be expensive.

* At present, small cars with efficient and clean diesel engines are probably the best option.

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Hybrid: Is a petrol-electric hybrid better than a good diesel?

Currently available hybrids have both an electric motor and a petrol engine. The models now available cannot be recharged from the mains, but that will change soon (see plug-in hybrids, below). At present, battery capacity is limited by the high cost of the most efficient types of batteries and by the weight of large battery arrays. The batteries also reduce the available luggage space in some models.

Some hybrids, such as Honda’s Insight, Civic Hybrid and CR-Z sports car, have the electric motor and petrol engine driving the wheels together. This ‘parallel’ arrangement (first diagram below) allows the petrol engine to be smaller, but these cars cannot run on electric power alone for short journeys.

A different arrangement is for the petrol engine to run a generator that powers an electric motor, which in turn drives the wheels. This ‘series’ configuration (second diagram) allows the petrol engine to run at maximum efficiency but tends to have limited power. Hybrids of this type will be appearing shortly.

Probably the best current system, called ‘series/parallel’ (third diagram), combines these by allowing the electric motor to drive the wheels on its own at low speed when there is enough charge in the batteries, but switches to the petrol engine at higher speeds and on longer journeys. The two can also work together to give more power when needed, for example going up hills. This system is used in the Toyota Prius, the UK-built Toyota Auris Hybrid, and various Lexus models.

       

Pros

• Hybrids consume much less petrol and have lower CO₂ emissions than conventional petrol-driven cars, and are competitive with the best small diesel cars. The saving in fuel consumption is due to the petrol engine being able to run at a constant, optimal speed when charging the batteries, together with other measures such as recovering some of the energy otherwise lost when braking or slowing down to charge the batteries (regenerative braking, see below), turning off the engine when not moving (stop-start, see below), improved aerodynamics, low rolling-resistance tyres, etc.
• The hybrids currently available are at their best in stop-start city driving (usually the most polluted areas) – especially those that can run on the electric motor alone, which emit no greenhouse gas and other pollution.

Cons

• However, hybrids are expensive to buy and complex.
• Fuel consumption gains are limited by using petrol rather than diesel engines, together with automatic gearboxes (the Honda CR-Z is the only hybrid on sale with a manual gearbox).
• Fuel consumption at higher speeds, notably for motorway-style driving, can be disappointing.
• Hybrid versions of cars not originally purpose-designed as hybrids (e.g. Toyota Auris) tend to have very limited luggage space in order to accommodate the batteries.
• Large hybrids (4x4s, people carriers and other large and luxurious cars) are no better for consumption and emissions than a medium-size conventional petrol car.

* Petrol-electric hybrids are competitive with efficient diesels and produce somewhat less pollution. They are a good choice especially if you do a lot of urban driving; their advantages are less clear-cut in rural areas.

Why aren’t there hybrids with diesel engines and/or manual gearboxes?

There are several reasons. The US market, which is a main one for manufacturers such as Toyota and Honda (the leading hybrid makers at present), demands automatics, and diesels don’t sell well in the US due to a combination of some very bad diesels in the distant past, and pollution regulations concerning soot and nitrogen oxides. (The main suppliers of the few diesel cars in the US are Volkswagen/Audi and Mercedes.)

In addition, hybrid technology is expensive and diesels would make it even more so. Toyota also claims that the automatic gearbox is needed for smoothness when mixing petrol and electric power in their series/parallel arrangement. On the other hand, Honda (which uses the rather different parallel hybrid layout) is now selling the CR-Z hybrid sports car with a 6-speed manual gearbox.

There are beginning to be signs of forthcoming diesel hybrids from European manufacturers such as Peugeot (which is not dependent on the US market) and Mercedes. Toyota sells a hybrid diesel truck in Japan, and diesel-electric hybrid buses (e.g. Dennis, and now Volvo) are beginning to be used in the UK in serious numbers, not just pilot schemes (e.g. in London, Reading and Oxford).

Other energy-saving features

Regenerative braking

Regenerative braking recovers some of the energy normally lost as heat in the brakes. Its first widespread use was in hybrids, and all forthcoming hybrid and electric models have it. When the car brakes or goes downhill the electric motor is reversed to turn it into a generator, and this charges up the car’s batteries while providing some resistance to help slow down.

For conventional petrol or diesel cars without an electric motor, a simpler trick is simply to disengage the alternator except when the car is slowing down or there is a heavy electrical demand. This reduces the alternator’s load on the engine most of the time, which helps a bit with fuel consumption. This is now done, for example, by Volkswagen (so-called ‘energy recovery’) and BMW (which misleadingly calls it ‘regenerative braking’).

Another possibility for the future is to store the captured energy with a flywheel or in a large capacitor, which can help to drive the car when extra power is needed.

Stop-start systems

The idea is to turn off the engine automatically when the car is stopped for any length of time, for example at traffic lights or in a traffic jam, and to restart the engine when it’s needed in a quick and seamless way. The engine goes off when you stop, depress the clutch and shift into neutral. It restarts when you depress the clutch again to shift into gear. This was first tried on a Volkswagen Golf model in 1991, and re-introduced on hybrids. It is now available on a growing number of both ‘eco’ and conventional models.

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Newly introduced and forthcoming models

At present virtually all the viable car options still use fossil fuels, so the discussion above is about more efficient use of fuel – greener rather than green motoring. But things may start improving quite soon. There will be more ‘conventional’ hybrids like the existing Toyota Prius and Honda Insight. Plug-in hybrids with batteries that can be recharged from the mains should start appearing within a year or so, and perhaps hybrid diesels. Hybrids will increasingly be able to go short distances (useful for commuting or shopping) on batteries alone – some of these models will be more like electric cars with low-powered internal combustion engines to get you to your destination when the batteries run out. Some fully electric models started coming onto the market early in 2011. Hydrogen-powered cars, either burning the hydrogen directly or using fuel cells to generate electricity, have been much touted in the recent past but seem to be further off – see our hydrogen page. We consider other fuel possibilities on our alternative road fuels page.

Major progress with both hybrids and electrics will depend on improving battery storage capacity, cost and lifetime, as well as developing infrastructure for recharging and/or exchanging batteries. A key issue is where the electricity for charging the batteries comes from – fossil fuels or renewables – and how the electricity grid will deal with the increased load.

Conventional petrol and diesel cars will make increasing use of energy-saving technologies, such as regenerative braking, stop-start systems, better aerodynamics, weight-saving, higher gearing, low rolling-resistance tyres, intelligent gear-change indicators, efficient automatic gearboxes, etc.

Conventional hybrids

Toyota and Honda will continue to put their existing hybrid technology into more of their European models – both companies already sell a much wider range of hybrid models in the US and Japan. Large numbers of hybrid models from other manufacturers, of various sizes and efficiency, are now available or coming onto the market in the US, and some of them will soon be sold in the UK. Some aim for low total fuel consumption, while larger models try to make luxurious 4x4s and people carriers more acceptable. However, in the UK they must compete with diesels, which can offer similar fuel consumption in a less complex, cheaper package. This means that the gains offered by conventional hybrids, especially outside urban areas, are less clear.

Plug-in hybrids

A number of hybrid models with mains-rechargeable batteries will be available soon. The iconic Toyota Prius is trialling a few test vehicles in the UK, with sales starting in 2012. Compared to the current version, more and better batteries will provide an electric-only driving range of about 30 miles at the expense of some boot space. A variety of others are also coming soon,

Toyota and Honda hybrids are sold as general-purpose cars, but some hybrids that put more emphasis on the electric side are being developed. These ‘extended range electric vehicles’ will be able to do short journeys, e.g. shopping or commuting, on their batteries alone without using any fossil fuel, but have a small internal combustion engine for longer journeys and in case the batteries run out unexpectedly. This avoids the problem of long charging times and non-existent charging infrastructure in mid-journey. However, as with existing hybrids, there are problems fitting in all the required gear and a large battery pack while providing adequate passenger and luggage space, particularly in cars not specifically designed as hybrids.

Purchase prices will probably be higher than present hybrids due to the need for higher capacity batteries, but running costs could be much lower if electricity is used most of the time. In addition, the Toyota Prius, Vauxhall Ampera and Chevrolet Volt plug-in hybrids will be eligible for the government electric-car subsidy discussed below. Recharging from the mains reduces carbon emissions compared to existing hybrids, but it is crucial to have renewable electricity for this to be a truly green solution.

* Plug-in hybrids may prove to be a good option until major improvements to battery technology make fully electric cars a good all-round choice.

Vauxhall/Opel Ampera and Chevrolet Volt

A very interesting example is the Vauxhall/Opel Ampera (photo; also to be sold as the Chevrolet Volt). It is already on sale in the US, and will be available in the UK in 2012. The Ampera will be advertised as an ‘extended-range electric vehicle’, i.e. primarily an electric car with petrol backup. It is a ‘series’ hybrid always driven by its electric motor, with a battery pack that provides a range of 30–40 miles. Beyond that distance, a 1.4 litre petrol engine drives a generator that powers the electric motor and recharges the batteries. For long journeys it can go a total of 350 miles before the petrol tank needs refilling, but if it is recharged between short journeys (which takes four hours from a household socket) petrol usage will be minimal. The manufacturer claims an overall equivalent of 175 mpg and 40 g/km CO₂ emissions.

The Ampera will be quite expensive (£29,000 after the government grant) – whether it will be a sensible option depends on your driving. It might be a good choice if you do a lot of driving and nearly all of your total mileage will be short journeys in electric mode, with the petrol engine used only a small fraction of the time. However, if more of your mileage will require the engine then the relatively poor petrol consumption would make an efficient, cheaper diesel car a better choice.

Audi A1 e-tron

Another is the Audi A1 e-tron, based on the small Audi A1 and also to be available in 2012. It has a range of about 30 miles on its battery pack, but also has a small Wankel engine for charging which allows it to go a further 124 miles on a tank of fuel.

Diesel hybrids

A number of manufacturers have shown prototype diesel hybrids, for example at motor shows. Here we mention a few models that should appear during the next couple of years.

Peugeot 3008

Peugeot will soon launch the 3008 HYbrid4. Aimed at using standard components as much as possible, the configuration is unusual: a 2.0 litre diesel engine driving the front wheels, and an electric motor driving the rear wheels. The gearbox is essentially a manual design shifted automatically by electronics, for efficiency. The car can run in diesel-only front-wheel drive, electric-only rear-wheel drive with zero emissions but a range of only a few miles, and a combined four-wheel-drive mode. The system is designed to fit other models in the Peugeot/Citroën range as well.

Mercedes-Benz E300

The Mercedes-Benz E300 BlueTEC diesel hybrid is due to be on sale at the end of 2011. This has a 2.2 litre diesel engine combined with an electric motor and an automatic gearbox. The motor assists the diesel engine when the car is accelerating and is reversed for the recuperation of braking energy in alternator mode, although it is also suitable for driving using electric power alone. Carbon dioxide emissions are just 109 g/km, low for such a big car.

Volvo V70

Volvo has begun testing a diesel plug-in hybrid based on the V70 model. Like the Vauxhall/Opel Ampera petrol hybrid, the aim is to be able to do short journeys of 20 miles or more using only battery power. Beyond that the diesel comes on, allowing a much longer driving range and conventional refuelling.

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Electric: are the new and soon-to-appear models a good solution?

The biggest problem for purely electric cars is that energy is stored in existing types of batteries at a much lower density than in petrol or diesel fuel. This means they need big, heavy, and very expensive battery packs. The weight limits performance, the size makes providing sufficient space for passengers and luggage difficult, and the relatively small amount of stored energy limits the range – this is the most serious problem. Progress is being made, but much more research and development is needed and it is a difficult and slow process – the descriptions below of small cars that only give short driving ranges speak for themselves.

Parking spaces with charging points to recharge depleted batteries, mainly in towns and cities, will help, but general coverage of the country will take a long time. Plans have been announced to install plug-in charging stations in London, Milton Keynes, the north-east and east of England, the Midlands, Greater Manchester, Scotland, and Northern Ireland but how far the £20 million allocated will stretch remains to be seen.

Charging time is also a serious problem. On long journeys even a ‘quick’ half-hour recharge at a charging station (photo) takes too long. A possible solution, if batteries are sufficiently standardised, is for ‘filling’ stations that can do a quick swap of discharged batteries for fully charged ones, as mentioned in connection with the Renault Fluence below.

In addition, the currently favoured battery type, lithium-ion, has to be very carefully made and recharged. If faulty or not treated carefully they can overheat and even start a fire. (This has been a problem with some laptop computer batteries.)

If all the cars on UK roads were electric rather than internal combustion, and if they were to recharge their batteries using the present mains electricity mix (which is mostly generated using fossil fuel), their improved efficiency would reduce carbon emissions by something like 50% compared to petrol and diesel vehicles. That helps, but we need clean, renewable electricity to do better.

Another problem is that shifting the energy source of all UK cars onto the electricity network is estimated to require something like 16% more electricity generating capacity, or around 10 gigawatts. However, rather than build more capacity, much of the increase could be absorbed by a smart grid combined with smart chargers that, whenever possible, work when the grid load is low (especially during the night) and thus require little new peak generating capacity. As a by-product, this could help in dealing with the intermittent nature of some renewable energy sources, such as wind and solar.

It seems clear that electric cars need to be designed differently from fossil-fuel ones. For example, heating the car in winter can rapidly drain the batteries, so unlike cars at present there needs to be excellent thermal insulation. The electric motors in these cars are small, relatively simple, and do not need a complex gearbox, but a large battery pack is required. Will the batteries be standardised, or will the motor industry emulate on a large scale the situation with many electronic gadgets and use batteries specific to each different model? Is the current, fairly conventional layout of front-engine, mostly front-wheel drive still the best?

* Lighter, cheaper batteries that hold much more charge, and which can be recharged more quickly, are essential – the improvement needed in both capacity and charging time might be a factor of four or five.

The government low-carbon car incentive

The previous government had announced a programme of grants to buyers of electric cars, starting in January 2011. These will provide a 25% discount up to a maximum £5000 in order to stimulate sales of these cars, which otherwise would be very expensive. The present government announced that this scheme will go ahead, but only for one year and limited to £43 million, enough for 8600 cars (since the eligible cars will probably all cost more than £20,000 and thus get a £5000 grant). For models that will only be available on lease the grant will be used to reduce the monthly leasing fees. After one year the scheme will be reviewed.

Note that both fully electric cars and plug-in hybrids are included in the scheme. The cars covered initially, their actual or projected dates of going on sale, and their base prices (without the grant) if known are:

• Smart Fortwo Electric Drive: mid-2012
• Mitsubishi i-MiEV: Jan 2011; £29,000 (see below)
• Peugeot iOn: Jan 2011; only on 4-year lease at £415 per month (see below)
• Citroën CZero: Early 2011; only on 4-year lease at £415 per month (see below)
• Nissan Leaf: March 2011; £30,990 (see below)
• Tata Vista: Summer 2011 for fleet customers; summer 2012 general sale (see below)
• Toyota Prius Plug-in Hybrid: Early 2012
• Chevrolet Volt: Early 2012 (see above)
• Vauxhall Ampera: Early 2012; £34,000 (see above)

The related programme to install large numbers of charging points around the country is mentioned above.

Fully electric examples

Many manufacturers have been developing fully electric models, and it is not always easy to tell which ones are actually going to be on sale and which are just research projects. Here is a selection from the more realistic end of the spectrum.

Nissan Leaf and Renault Fluence Z.E.

The Nissan Leaf (‘Leading, Environmentally Friendly, Affordable, Family Car’, photo) and the technically similar Renault Fluence Z.E. are family-sized 5-door hatchbacks. (The Renault will also be available in petrol and diesel versions, while the Leaf is designed around electric power.) The Leaf went on sale in the UK in March 2011. These cars have a nominal range of 100 miles, though this will vary greatly with driving conditions, terrain and weather. Their speed is limited to about 84 miles per hour. The cars have two charging connectors – one for a normal household connection, which takes about 8 hours for a full recharge, and a special high-current one for a quick recharge to about 80% of capacity in half an hour.

The Leaf will be built in the UK from 2013, and costs £30,990 – higher than had been originally announced. This is reduced by the £5000 government grant – see the item above.

The Renault will cost less, about £18,000 when it goes on sale in 2012, but the purchase price will not include the expensive battery pack, which will be leased from Renault for £75 per month. This means the owner is protected against battery failure or a drop in performance.

A possible solution to the need to get going quickly when the batteries are discharged is being planned for the Renault by a company called Better Place. Networks of service stations will replace discharged batteries with fully charged ones. Their first operation is planned for Israel, where they are based. It will be interesting to see how successful this is and whether it becomes available for other models.

An important factor when considering the high purchase price is that the running cost will be far lower than for a fossil-fuel car, but will, of course, depend on the price paid for electricity when recharging. Nissan’s estimate of 0.3p per mile, producing a saving of £1500 per year if the car is driven 10,000 miles, is based on a cheap night-time electricity tariff; the AA estimates a cost of more like 2p per mile.

In a recent review, the consumer group Which? thought the Leaf was the only electric model that could replace a family hatchback. However, they found the range of the Leaf to be only 70-odd miles. Although ‘exhaust’ emissions were zero, they estimated that recharging the batteries on normal electricity was roughly equivalent to CO₂ emissions of around 106 g/km – some conventional ‘eco’ cars do better than this – but if you have solar panels and recharge when the sun is shining you do better than this. They also pointed out that the cost if the batteries need replacing is not yet clear.

Mitsubishi i-MiEV, Peugeot iOn and Citroën C-Zero

The i-MiEV (‘Mitsubishi In-wheel motor Electric Vehicle’) is shown in the diagram; note how different the layout is compared to a conventional car. It is a small car is already on sale in Japan for fleet users; it became available in the UK at the start of 2011. It has four doors and four seats. Despite its name, the design has now evolved and there is just one electric motor rather than individual in-wheel ones. Like the Leaf/Fluence, its range is a nominal 100 miles and it has both a normal, slow-charging mode and a quick, half-hour mode to get to 80% using a high-current three-phase supply. The price is £29,000. As with the Nissan Leaf, the £5000 government grant to reduce the purchase price has been assumed. The estimated running cost is 1p per mile for recharging, together with very low servicing costs and no road tax.

The Peugeot and Citroën versions are now available; they claim a range of only 80 miles and will only be available on a 4-year lease at £415 per month.

Tata Vista

This car, based on the Tata Indica that is sold in India, is a fully electric four-seat family car. The range is claimed to be 110 miles, with a top speed of 71 mph. It will be built in a new factory in the West Midlands. To start, 25 cars are being tested as part of the Coventry and Birmingham Low Emission Demonstrator (CABLED) programme. In summer 2011, the car will be launched in the UK and other selected European markets, but it will be restricted to fleet customers to start with. A launch for the general public is planned for summer 2012. The battery is Swedish, the drivetrain Canadian, and the rest of the kit comes from India.

Mini E

The BMW Mini E claims a range of 150 miles, a top speed of 95 miles per hour, and rapid acceleration. It has recently been under test with a small number of users in the UK, Germany and the US, in a preliminary version with the back seat removed to provide space for the batteries. However, in real conditions the range has averaged about 100 miles, and as little as 40 miles in cold weather. Like all fully electric models, and unlike a plug-in hybrid such as the Vauxhall/Opel Ampera, when the battery runs out unexpectedly there is no backup. This is the most serious problem raised by the testers, not surprisingly. It is not clear what BMW plans to do next: there are reports of an all-electric design not based on the Mini, and rumours that a small petrol engine might be added as in the Ampera.

Smart Fortwo ED

The very small, two-seat Fortwo Electric Drive is externally similar to the current Smart Car petrol and diesel models. The range on its lithium batteries is about 70 miles. A full charge takes eight hours and costs about £2, but a boost from 20% to 80% is quicker at three hours. The top speed is limited to 62 miles per hour. Like the Mini E, this small car is being evaluated by leasing it to 100 drivers in the UK under a government-sponsored scheme. The electric motor drives through a fixed, single gear ratio, and so is apparently much smoother than the automatic gearbox on some Smart models. The car will be available only on a 4-year lease, starting early in 2011.

* Some of these forthcoming models may prove to be a viable but expensive option for short journeys, but in order to be a good general-purpose choice the technology will have to improve by a large factor.

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Road Tax Rates

Road tax is changing gradually to penalise inefficient cars and reward greener ones. For recent cars the rate depends on carbon dioxide emissions. Here are the 2011–2012 12-month rates for petrol and diesel cars; 6-month rates and cars using other fuels can be found elsewhere.

Cars registered before 1 March 2001 (based on engine size)

Up to 1549 cc: £130

Over 1549 cc: £215

Cars registered from 1 March 2001 (based on CO₂ emissions)

To further reward green cars and penalise inefficient ones, the road tax for many new cars is now different in their first year – this is shown in the last column.

* Cars that were registered before 23 March 2006 and have a CO₂ figure over 225 g/km are all included in Band K.

The overall trend of increasing both rewards and penalties is expected to continue in the future. The target is for an overall average of 130 g/km CO₂ from 2012 and 95 g/km by 2020.

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