For years car makers thought an engine needed at least four cylinders to deliver reasonable power and refinement. In recent times some three-cylinder engines have appeared and now you can buy Fiat's trendy 500 and soft-top 500C with a two-cylinder engine called TwinAir. But can two cylinders really cope where four were once the norm?

TwinAir makes up for its cylinder shortfall and its tiny capacity - just 875cc - with a turbocharger and some clever design features. It's the latter which makes TwinAir remarkably smooth when revving: there's a balance shaft carrying rotating weights which spins at the same speed as the engine to smoothe out the natural vibration of the two-cylinder design. The engine also incorporates Fiat's MultiAir system which controls the engine by altering the amount the valves open rather than by using a throttle. Engine efficiency improves as a result. Thanks to the turbo, the TwinAir engine produces 85bhp, and that's enough to give the 500C a 108mph top speed and 0-60mph acceleration in 11 seconds - more than enough to keep up with other traffic. Yet in the hands of most drivers it should return well over 60mpg. It's little wonder that the TwinAir engine won International Engine of the Year in May.

Of course, it's the cheeky and cheerful throwback styling which attracts many buyers to the little Fiat - and the availability of the soft-top 500C, which has few real rivals at the same price. The edges of the roof and the rear pillars are fixed, but the centre part of the roof is a fabric panel which can be electrically folded part-way or all the way to the rear, giving you the maximum of fresh air. The only drawback is that the folds of the roof stack where the rear window would be, reducing visibility rearwards.

The 500C a likeable package which is a lot more than simply a trendy shape: it's stylish, practical, economical, relatively refined and has performed well in crash tests. The clever TwinAir engine simply adds to its appeal.

www.fiat.co.uk