With car makers keen to reduce emissions and save fuel these days, one obvious place to start is weight reduction. And what better way to cut unnecessary weight than to streamline a car’s engine – downsizing is the new black.

Fiat has long held a reputation for engine development, and it’s now gone and halved the cylinder count for its popular 500.

Dubbed “Twinair” the 500’s 0.9-litre, twin-cylinder petrol unit offers significant savings over a larger four-pot motor in terms of economy, emissions and, unsurprisingly, weight. Fiat is clear that that this engine will be the first of many, and the aim is to reduce emissions levels to new lows well in advance of any country-specific legislation.

The upshot for the consumer is a 500 with more character. When it first appeared some observers were disappointed by its lack of a technological highlight. Sure, the car was a faithful, if larger, reproduction of a popular classic. It didn’t boast anything groundbreaking, though. That’s changed with the arrival of Fiat’s Twinair engine, and it’s difficult to think of a more appropriate home for this remarkable little motor.

There’s no question that the technology underpinning the Twinair engine is impressive. Borrowing Fiat’s recent Multiair development – where airflow into the engine is managed electronically cylinder by cylinder through the unit’s inlet valves, not the throttle – this two-cylinder engine is the product of a clean-sheet design, a new type of turbocharger and a few hundred million Euros. In reality Fiat’s achievement is worthy of significant praise. In 85bhp trim – 105bhp turbo and 65bhp non turbo variants are scheduled to follow – you get the power, accelerative punch and cruising ability of a traditional small capacity four-cylinder petrol car but with the economy and, crucially, emissions of something much smaller.

How does 68.9mpg and 95g/km CO2 sound?

Granted, the 500 is hardly a big car, but that’s a 15 per cent CO2 reduction over a regular 1.2-litre petrol 500. If you opt for Fiat’s “Dualogic” semi-auto gearbox, the numbers are better still, at 70.6mpg and 92g/km respectively.

With all that data in mind, it only takes a minute to realise how much this particular 500 could save you in fuel and tax over the course of a few years.

Since its launch the 500 has sold well, but was in need of something special to lift it above its numerous rivals. So add in the Twinair’s addictive engine note, smooth power delivery and ample reserves of torque and this added layer of enjoyment is the icing on an already mouthwatering cake.

Fiat 500 Twinair Sport, from �12,065