Fiat 500: Open your mind to the putter-putter

Car fans will come over all nostalgic when they hear Fiat's 500 TwinAir engine. Photo / Supplied

It's all about the sound. Low emissions, wallet-easing economy, and worthy greenness might be the po-faced agenda - but actually it's acoustics. Trouble is, today's over-regulated world fails to differentiate between pleasing sound and mere noise.

So most small cars nowadays are quiet. The only real emotive part missing from the cute retro-fest that was Fiat's reincarnated Fiat 500, launched to great success three years ago, was the sound it made.

The little car looked as if it should putter-putter like its tiny, air-cooled, two-cylinder ancestor did half a century ago. But it didn't. Instead it sounded like, well, a Toyota Yaris or something.

Since then, however, the engineering elves have been busy. I am driving a brand new 500 in a cheerful sky blue and all is right with the world.

That is because it is making the right sound. It putters. It has a slight vibration as it accelerates from low engine speeds. The shape of the soundwaves fits the shape of the car and the 500, finally, is complete. It's the car it should be.

That's because under the bonnet is a new two-cylinder engine whose two pistons reciprocate vertically in unison, just as the old 500's did.

But there are crucial differences. The new engine's capacity is not 499.5cc but 875cc. It is cooled not by air but by water, as modern engines are. It produces not 13kW but 64kW - an impressive increase, it must be said.

And it has a very clever induction system, because in essence it is half of that most cleverly conceived engine for many years, the Fiat/Alfa Romeo MultiAir.

This halved version is called TwinAir, but the principle is the same. Instead of using a conventional camshaft, the inlet valves are opened hydraulically.

The exhaust camshaft carries an extra set of lobes, each shaped to represent the greatest possible inlet-valve opening for the longest possible time. Each of these lobes moves a hydraulic piston, and the oil it displaces is forced along a tube to operate another piston connected directly to the inlet valve.

The clever part is this: an electronic solenoid valve bleeds off the pressurised oil in a very tightly controlled way, so making the inlet valve open only as far and for as long as is needed.

This means the engine can be tailored for every speed range and acceleration request, pulling hard at low speeds when asked and using the valves themselves as the throttle.

There's a turbocharger, too, and the result is one efficient engine - further helped by the fact that two cylinders generate less friction than four. No petrol-fuelled four-seater emits less CO2: 95g/km with a five-speed manual gearbox, 92g/km with the semi-automatic.

Trouble is, it's hard to drive the 500 TwinAir the right way to maximise the economy potential, even though the engine pulls far harder from low speeds than the deep note, the gentle vibro-massage, and your own conditioning suggest it should.

So eager is it to go, that you end up keeping it in a lower gear - third is particularly versatile - and letting the little Fiat punch its way through traffic, around corners, up hills.

And when you feel slightly cheated that the acceleration has suddenly ceased, you realise that you have just hit the rev-limiter at 6,100rpm. The deep buzz makes you think the engine is running at half that speed.

A balancer shaft cancels the vibration once the engine is spinning briskly, and, unlike the old 500, the new one doesn't bounce comically up and down as the engine is spun on the starter. An Eco button reduces the engine's torque output from 145Nm to 100Nm should you need to be especially economical and can't discipline your own right foot. You'll try it once and never touch it again.

For the rest, this 500 is like the others in the range with better steering and a much more comfortable ride.

Some people won't like the TwinAir's sound, feel, and driving characteristics, and will think it odd. They have closed minds and miss the point. I think it's brilliant and I love it. Would I have one? You bet I would.

- THE INDEPENDENT