THE environmental issue is the greatest challenge facing the motoring industry today. How to find a lean, green alternative to an internal combustion engine powered by fossil fuels, which has been used since the 19th century, is a question that is vexing the industry.

Which route do car manufacturers take? The answer to that is, of course, the holy grail – no one wants to invest billions of pounds in the next Betamax project. Some, such as Saab, have been working on flex-fuel technology and its BioPower option, which is available across the company’s product range, means that cars can run on bioethanol E85. This is produced from crops such as wheat and sugar beet and reduces a car’s CO2 emissions by between 50 and 70 per cent of the petrol equivalent.

Even less radical changes, such as the EfficientDynamics programme introduced by BMW, are a huge step forward. This technology, also available on the MINI range, allows fuel consumption improve by almost a quarter and emissions to drop by as much as 19 per cent. But, importantly for those who think going greener comes at the expense of performance, engine outputs will increase by up to 21hp.

Alternatively, there is the option to power cars using fuel cells (a technology that has also been extended to motorcycles), electricity, cleaner fuels, hybrid versions of any of the above – you mention it and the industry has contemplated it, but without a coordinated strategy as yet.

Half the problem is that the authorities are confused about policy. Is the London congestion charge designed to cut congestion or emissions? When Transport for London mooted making driving in the charging zone free for cars that emit less than 120g of CO2 per kilometre, there was a rush to dealers to purchase the latest Smart Fortwo (116g/km), BMW 118d (119g/km) and others.

In 2006 the UN released its Livestock’s Long Shadow report, which gave warning against the environmental impact of the proliferation of the global food industry, announcing that the livestock sector generates, at 18 per cent, more greenhouse gas emissions (in a CO2 equivalent) than transport.

So in these confusing times, where cows appear to be worse polluters than cars, what can you do to make a difference? The most obvious – although not always practical – solution is to buy a car that puts out fewer emissions. If a visit to the car showroom is not on the agenda, then even small changes, such as making sure your tyres are inflated to the correct pressure, can help. Planning your journey to drive at less busy times, if possible, is helpful (and less stressful). Driving at 50mph is up to 15 per cent more fuel-efficient than at 70mph and a lot more emissions friendly than driving in stop-start traffic at 5mph (50 per cent more friendly, in fact).

But if all the green issues fail to persuade people to make a change in their driving habits, what about the impact on their wallets? After the deferred fuel duty rise of 2p a litre in October last year, we are due another 2p a litre rise in April (yes, you had forgotten that little time-bomb in the Chancellor’s 2007 Budget, hadn’t you?) which will push the price of unleaded to about the 105p a litre mark. Diesel – once cheaper than unleaded – is now passing the £5 a gallon milestone, which is not good news for hauliers and those long-distance drivers who rely on better fuel consumption figures. Almost a million diesel cars were sold in the UK in 2007 – will we see a switch back to petrol cars soon?

And yet the green motoring debate is a double-edged sword. Earlier this month, Tata unveiled the Nano, which it hopes will open up motoring to a million new car-owners a year in India. Do we get on our environmental soapbox and rail about the emissions disaster this will be – or do we deny so many people the right to cheap cars that we simply take for granted? Confusing times indeed.

THE DIFFERENT CATEGORIES OF GREEN CARS
Green cars come in several categories, including:

Conventional but mean: The most frugal car is the VW Polo Blue Motion with 74.3mpg and emissions of 99g/km; there is a diesel Smart Fortwo on the way that does 85mpg and puts out 88g/km. The MINI Cooper D, Citroen C1 and its cousins the Peugeot 107 and Toyota Aygo are also in this category.

LPG & CNG: Any car can be converted to run on liquefied petroleum gas, which while still a fossil fuel, is about half the price of petrol and emits less CO2 . Volvo claims that compressed natural gas is cleaner still, though filling stations are few and far between so it is offered in a dual-fuel package. Volvo is working on a home-fill station using domestic gas supplies.

Hybrids: Electric-petrol hybrids use batteries in town and conventional engines for longer journeys. The Toyota Prius set the pace closely followed by the Honda Civic IMA. Four-wheel drives are joining the field – Lexus RX 400h and soon a Porsche Cayenne.

Pure electric: Not fast, not roomy, limited in range, but 100 per cent emission-free and thus free of congestion charge and road tax. The tiny Reva G-Wiz is the top-seller, the Italian-built Elettrica the cutest.

Biofuel: Controversy rages over these fuels from plants, but E85 pumps (85 per cent ethanol and 15 per cent petrol) are becoming more familiar. A second generation biofuel made from waste may meet many objections. Saab 9-5 and Ford Focus FFV lead the field.

Hydrogen fuel cells: If hydrogen can be produced cheaply, this could be the cleanest. Honda’s FCX Clarity will arrive this year; GM and Ford are close behind.

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