What Car? Q&A - Green special - What's the best green car?

I need a car, but I also want to do my bit for the environment. What are the greenest cars?
Tony Crosbie

A: The cleanest car on the market will probably be the Volkswagen Polo Bluemotion, when it goes on sale in September.

The Polo Bluemotion is powered by a 79bhp 1.4-litre diesel, and returns 72.4mpg on the combined cycle.

Thanks to improved aerodynamics, reduced weight and modified gearing, that's more than 12mpg better than a standard 1.4 diesel Polo.

It emits 102g/km, which means it will beat the next-best supermini, the Toyota Aygo1.0 VVT-I +, and its siblings the Citroen C1 1.0i Vibe and Peugeot 107 1.0 Urban (all essentially the same car).

Click here to see a table of the most environmentally friendly cars in each class.