Road Test: Volkswagen Golf 1.4 GT TSI 3dr

Funny how the game of one-upmanship can play out with car manufacturers. At one point, if you had a turbo or supercharger then you were pretty special. Then BMW and Jaguar, among others, fitted two turbochargers.

And now it's finally the turn of Volkswagen to go nah-nah to its rivals, because the German firm has managed to fit a turbo and a supercharger onto one petrol engine and dumped it all in the Golf TSI. Talk about overkill.

However, if you sit and think about it for a minute, it starts to make sense. After all, when you have only got a turbo, it relies on the exhaust pressure to force more air into the cylinders.

By its very nature, there's always going to be some lag, even if manufacturers have trimmed this almost to zero. Once running, though, it's efficient.

The supercharger, on the other hand, runs off the engine itself. Plant your foot and you have instant go, but then it also uses up some of your crucial horses because it's driven off the crankshaft. Combine the two and you've got the benefits of both.

Which is precisely what the TSI has managed to do. Jump into it for the first time and you wonder why, apart from the obvious complexity, other cars aren't engineered this way - you've got an efficient 1.4-litre engine that produces 168bhp.

This is about more than simple figures, though, because it's the instant power that makes all the difference. 147lb ft is available from not far off idle, so that around town and during cruising, the TSI is really responsive.

Here comes the clever bit. Above about 3,000rpm, the turbo alone can provide enough boost so VW has fitted the supercharger with an electromagnetic clutch which dials it out above this point. Which roughly translates as more efficiency.

It's all done very smoothly, so the only way you know the supercharger isn't working is because you can't hear its faint whine any more.

The good thing about all this is that you can generate decent power levels off a relatively small engine, so company car users will love it because it only produces 178g/km of CO2, thus lowering their tax contribution, while private buyers will appreciate the 38.2mpg.

You can expect this technology to roll out across other Volkswagen products soon and it might even replace more normal engines. Keeping up with the Joneses will prove ever more difficult.