More frugal and more powerful than a naturally aspirated unit. The future.

Downsizing is the new buzz word at Volkswagen. But its not that existing models are getting smaller – it’s engines. Driven by spiralling fuel prices and ever-stringent emissions regulations, the push is on to introduce a range of small-capacity units with low fuel consumption and small CO2 emissions, but big power.

It’s a tough task, but if the first of VW’s new engines, the Twincharger unit driven here, is anything to go by VW could be on to something big. Fitted to the new Golf GT, the 16-valve 1.4-litre unit utilises both a supercharger and turbocharger. The supercharger, which operates at a maximum of 1.8bar, boosts low-end response and flattens the torque curve, while the turbocharger, which hits 2.5bar, strengthens the top end. Added to this is VW’s FSI direct-injection petrol technology, delivering fuel at high pressure for added combustion efficiency.

The new engine develops 168bhp at 6000rpm and 177lb ft of torque from 1750rpm to 4500rpm, 20bhp and 30lb ft more than the naturally aspirated 2.0-litre FSI unit. But it’s the way the new engine performs out on the road that impresses the most. There’s serious pull from the off, with 148lb ft available from 1250rpm, while it is also responsive, flexible and linear well beyond 2400rpm, where the supercharger begins to disengage.

At this point, the turbocharger is already providing a decent boost, having entered proceedings at 1500rpm, so you’re unaware of any change in character. With a specific output of 120bhp per litre, in fact, it feels positively sporting.

VW puts the Golf GT’s 0-62mph time at 7.9sec, down from 8.8sec in the 2.0-litre FSI. A better reflection of the engine’s nature, however, is the fifth gear 50-75mph time, which is reduced by a whole second to just 8.0sec. Top speed is up 6mph to 136mph.

Amazingly, it does this while using less fuel than the 2.0-litre, averaging 39.2mpg against 37.2mpg on the combined cycle. CO2 emissions are reduced to 173g/km from 182g/km, while VW also claims lower noise levels throughout the rev range; it whistles and grinds like an Impreza, but always sounds smooth.

If this is the future for the petrol engine, the trend towards diesel powerplants could already have hit its peak. The Twincharger really is that good.

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BriMarsh 15 September 2011

Re: VW Golf GT TSI 170

Test date 30 September 2005? Isn't the Twincharger now dead?