It isn't electric, it isn't a hybrid, and it doesn't run on bio-fuel. Here we have a perfectly conventional BMW 3-Series, but one that has emissions that rival the most environmentally efficient machines on the market today. For with the BMW 320d Efficient Dynamics you have to make few compromises with the familiar joys of driving – if you want or need to drive your BMW hard it will take you to 60mph in around 8 seconds and on to a top speed of 137mph (though obviously the planet, and your bank balance, will pay a penalty for such self-indulgence).
Driven more sensibly it can return an impressive 68.9mpg, and pump out a mere 109 grammes of carbon-dioxide per kilometre travelled. That's around the same as the last generation model of the Toyota Prius, the default green choice for so many, and not very far behind the current model Honda Insight hybrid. Yet with the BMW you don't have to give up any boot space for batteries. You don't have to drive something a little bit awkward-looking. And you don't have to give up your premium badge, if you're bothered about such things.
The reason the BMW is so green is because the engineers have concentrated on taking its diesel power plant to yet a further pitch of perfection. Slimmer wheels and tyres and a stop-start function also help. The old internal combustion engine gets an unsympathetic press, but in the right hands it can be green. The Honda Insight and the Toyota Prius are also sound choices, as are small diesels such as the Smart and Citroen C1, and electric vehicles such as the Vauxhall Ampera and Nissan Leaf, when they arrive; but the BMW has the best blend of abilities, if you can afford it. The ultimate green driving machine, you might say. Available to order now for autumn delivery.
Sean O'Grady is The Independent's economics editorReuse content