To distract the world from real transport solutions, the automotive lobby promote the idea of "clean" cars. This usually implies alternatives to oil, or reducing toxic emissions from exhaust. More difficult problems go ignored.

A better approach is to see technology only as part of a wider effort to reduce car use and the problems it creates.

"Clean" cars can still result in un-sustainable energy consumption, greenhouse gas emission, urban sprawl, road construction, massive amounts of non-recyclable waste, road accidents, traffic congestion, obesity and poor health, inequitable mobility, and the erosion of city life.

Replacing old cars with new ones does not necessarily help the environment. A large part of the environmental damage caused in the lifecycle of a car is in construction and disposal. Keeping existing cars well tuned, and using them less is often a better alternative.

Elsewhere emission vehicles, specifically hydrogen, battery-electric, and compressed air cars have all been touted as solutions to urban air pollution. However the larger problem of producing clean energy is not solved, just transferred to some other place.

Diesel is currently by far the dirtiest fuel choice for private cars. However a double standard in the Euro-I through Euro-IV emission regulations has lead to the promotion of the image of a "clean" diesel car. Euro-IV diesel cars are allowed to emit three times as much nitrous oxide and carbon monoxide as Euro-IV petrol cars. In 2006 no diesel car came anywhere near meeting the minimum emissions standards in California. Detailed emissions data for all cars sold in the UK are available from the VCA database.

Biofuels can at best only power a small fraction of today's vehicle fleet, at the expense of rainforest and agriculture. With current technology biodiesel and ethanol have the added disadvantage of increased toxic exhaust emissions.

Petrol-electric hybrids achieve a 10-30% reduction in emissions and fuel consumption. Many car makers overstate the advantages of hybrid systems by comparing them to more powerful cars, outdated emissions standards or more powerful versions of the same car.

Alternative fossil fuels such as CNG and LPG offer similar advantages to hybrid cars. Existing petrol guzzlers can be converted at a fraction of the (environmental and financial) cost of a shiny new hybrid.

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