In an eco-marathon, you normally expect the winner to be a hybrid, a diesel or some other super-frugal -and usually underpowered- car. Well, in the Fleet World MPG Marathon the champion had no less than 431-horses kicking and screaming to be unleashed under its bonnet.

You read that correctly: the LS3 6.2-liter V8-powered VXR8 – essentially a Holden HSV rebadged as a Vauxhall for the UK market- won the two-day, 350-mile economy trial.

How did this happen? There’s a simple explanation: this award wasn’t given to the most fuel efficient vehicle in absolute numbers, but to the one that recorded the highest percent improvement over the official fuel consumption figures.

The super-fast Vauxhall was driven by Top Gear Online editor, Chris Mooney, while Vauxhall archivist and eco-driving expert, Andrew Duerden, occupied the passenger seat.

Mooney was able to improve the VXR8 official fuel consumption of 21.0 mpg UK (equal to 13.4 lt/100 km or 17.5mpg US) by 53%, dropping it down to 32.14 mpg UK (8.8 lt/100 km or 26.7 US mpg).

“It just goes to show that the person behind the wheel can make a massive difference to fuel costs and carbon emissions”, said Mooney. “And, of course, that a 6.2-liter V8 is a very sensible choice of engine in the right hands.”

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