Fiat 500 TwinAir

This is the engine for which the Fiat 500 has been crying out. The characterful two-cylinder delivers a remarkable mix of diesel-rivalling efficiency and strong straight-line pace. Adding to its appeal is a characterful soundtrack, as well as an eagerness that suits the trendy city car right down to the ground. Better still, the TwinAir demonstrates that, from an environmental point of view, there’s still plenty of life left in the traditional internal combustion engine.

It’s a case of back to the future for the latest version of the 500. The funky Fiat’s retro lines are a clear nod to the Fifties’ original, and now, bosses are looking to the past with an all-new engine for the stylish city car.

As with its legendary ancestor, the 500 is now available with a tiny two-cylinder unit. Promising 95g/km emissions and 68.9mpg economy, the TwinAir is claimed to be the most eco-friendly petrol engine on the planet – and Auto Express was first to try it in the UK.

Video: watch CarBuyer's video review of the Fiat 500

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Unlike the wheezy 13bhp original, the newcomer doesn’t deliver penny-pinching efficiency at the expense of performance. Thanks to the addition of a turbo and MultiAir variable valve timing, the 875cc unit offers a remarkable 85bhp.

Fire up the powerplant, and you’re left in no doubt about its two-cylinder layout, as it settles to a distinctive offbeat idle. On the move, the characterful sound is more like that of a motorbike than a car. Yet the engine always feels smooth, even when it’s extended to the red line.

However, the real surprise is the strong performance. A muscular 145Nm of torque is delivered at only 1,900rpm, giving punchy low-speed responses and strong overtaking pace. The 500 even feels comfortable on motorways, where keeping up with fast-moving traffic is no strain.

An Eco mode reins in the torque to 100Nm in a bid to cut the amount of fuel the TwinAir uses, and the standard gearshift indicator and stop-start system further boost efficiency. Go for the £730 optional Duologic semi-automatic transmission, and CO2 emissions drop to 92g/km, while economy increases to 70.6mpg.

Elsewhere, the car is the same as any other 500 – and that’s no bad thing. The cheeky looks still turn heads, and we love the neatly designed and well built cabin. It can’t match the MINI for driving fun, but the Fiat is agile and the five-speed manual gearbox serves up slick shifts.

Prices for the TwinAir start at £10,665 in entry-level Pop hatch guise, and rise to £16,065 for the top-spec 500C byDiesel cabrio. The two-cylinder line-up will expand next year to include a 65bhp normally aspirated car and a hot 105bhp model.

Rival: Toyota iQ

Clever packaging makes the extremely compact iQ one of the smallest four-seaters on the road – although rear space is very cramped, especially behind the driver. Strong refinement and excellent build quality are plus points, but the 1.0-litre engine is outperformed by Fiat’s 875cc unit.