Audi A1: revealed - Under the bonnet

The four engines are ideally suited to the downsizing trend that is behind Audi's decision to offer a car as small as the A1. All are small-capacity direct-injection turbocharged units, promising good fuel economy with no loss of driveability. Naturally, there's an emissions side to the story, too – the 89bhp 1.6-litre TDI diesel emits just 99g/km of CO2, which makes it road tax-free in the UK.

There's also a 104bhp version of this engine, but the two most important offerings for the UK, with taxation and fuel prices in mind, will be the TFSI petrol units – an 85bhp 1.2 that should be good for 55mpg out of town, and a 120bhp 1.4. With the optional seven-speed semi-auto gearbox (S tronic), the 1.4 is as economical as the 1.2, and it's only marginally worse with the six-speed manual.

An engine stop-start system that helps you save fuel in urban traffic is standard, as is brake energy recovery to lighten the load on the electrical system. You're even given a bit of coaching in the art of economical driving – the ‘driver information centre' displays your consumption and how much fuel is being drained by the climate system or window defrosters, and also advises you of the ideal points to change gear.

The A1's Polo roots dictate the choice of suspension – this is the only current Audi without an independent set-up at the rear – but the tuning is biased towards the sporty. Direct steering and an electronic differential lock are said to help the car turn sharply into corners and put its power down better through them, and there'll be the usual Audi option of a firmer and lower S line set-up, with appropriate body add-ons. Wheels of 15, 16 and 17 inches in diameter will be offered.