It may not be a streamlined hybrid, a futuristic electric vehicle or a snazzy biofuel car, but a distinctly boxy diesel Volvo has won What Car? magazine's award for the year's greenest car.

A small family car with carbon emissions on a par with Toyota's Prius, the Volvo S40 DRIVe received the award today from London mayor Boris Johnson. Vauxhall's Ampera electric car and US electric car-maker Tesla also received awards.

Johnson said: "There are clear incentives for manufacturers to raise the bar higher and higher to design less gas guzzling cars that take hundreds of pounds off consumers' fuel bills. This is good for the planet, good for the economy and great for the driver."

What Car? editor Steve Fowler said of the winning Volvo: "It's not just about a low CO2 figure. The S40 is great to drive, safe, has enough space for the family and, crucially, is cheap to run, too."

Ford, the US motoring giant which owns Volvo, lost out to Toyota in the battle for trophies between major car manufacturers. Toyota's Avensis 2.0 D-4D (CO2 emissions of 135 grammes per kilometre) won the best family car award, while Toyota subsidary Lexus picked up the prize for the greenest 4x4 with a petrol hybrid SUV, the RX450h SE-L (148g/km).

The winner of the technical award, Vauxhall's electric Ampera, is expected to debut in its US model the GM Volt in 2010 and arrive in the UK by 2012. Vauxhall's parent company General Motors claims the Ampera will change the image of electric cars by combining a 100mph top speed with an electric motor capable of driving 40 miles and a petrol engine which can increase the car's range to several hundred miles. Most of today's production electric cars, such as the G-Wiz, have a range of less than 100 miles.

Two notable omissions from the winners' list were Honda's hybrid Insight — which is the same size as the Volvo S40 DRIVe but has lower emissions — and the next generation Prius, which is set to go on sale later this summer.

Fowler warned the recession had made cars' environmental credentials a low priority for consumers. "Green issues are still a hot topic, but it's fair to say that they are not right at the top of car buyers' priorities at the moment. It's just as well then, that green cars will save you plenty of cash at the fuel pumps and will likely be worth more than other cars when you come to sell."

The winners:

Supermini

Fiat 500 Start&Stop £9,700, 113g/km, 58.9mpg

Small family car

Volvo S40 1.6D DRIVe S £17,495, 104g/km, 72.4mpg

Family car

Toyota Avensis 2.0 D-4D T2 £17,545, 135g/km, 55.4mpg

Executive car

BMW 318d ES £24,235, 123g/km, 60.1mpg

MPV

Citroën Grand C4 Picasso 1.6 HDi £19,095, 140g/km, 53.3mpg

4X4

Lexus RX450h SE-L £50,460, 148g/km, 44.8mpg

Sports car

Mini Cooper S £16,575, 149g/km, 45.6 mpg

Luxury car

Audi A8 2.8 V6 FSI SE £49,970, 199g/km, 34.0mpg

Technology

Vauxhall Ampera

Editor's award

Tesla