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The new Infiniti QX50 crossover is trying to reinvent the petrol engine

Infiniti’s new BMW X3 rival has a very trick turbocharged engine...

New crossover alert: it’s Infiniti’s turn to make a posh mid-sized SUV. This is the new QX50. And other than it being reasonably handsome and, from the one picture we’ve had through so far, quite brown, it’s a fairly unremarkable thing. Until, that is, you get to the engine. 

The QX50 is the first Infiniti – and the first car in the world – to be sold with a variable compression ratio engine. We’ll not delve into the nitty-gritty of how internal combustion engines function because it’s almost the weekend and you probably have turkey to be Thankful for. Suffice it to say that compression ratio is the technical term for the difference in volume in an engine’s combustion chamber when the piston is at the top of its stroke to the bottom. 

The higher your compression ratio, the more efficiently the engine combusts its fuel. Bad news: your engine is susceptible to ‘knock’, or ignite the fuel at the wrong moment. Which gets messy and expensive quite rapidly. 

What Infiniti’s new ‘VC-Turbo’ 2.0-litre four-cylinder does is vary the compression ratio between a lowly 8:1 when you want maximum attack horsepower, and a Mazda SkyActiv-high 14:1 for ultimate efficiency. By mechanically altering the pistons’ reach, Infiniti says it’s increased fuel efficiency by up to 35 per cent versus the old QX50’s V6.

Meanwhile, the 2.0-litre motor develops 264bhp and 280lb ft, and Infiniti insists it can be comparatively as efficient as a diesel. As diesel sales slide in Europe, could this be Infiniti’s moment to step up to the big leagues?

The CVT ‘gearbox’ might be a bugbear – the QX50’s VC engine is only available with a continuously variable transmission. Still, Infiniti says the AWD version can reach 62mph in 6.3 seconds and do 143mph, which is none too shabby for a 2.0-litre SUV.

The other headline ability of Infiniti’s Mercedes GLC rival is a suite of self-driving assist functions called ProPilot, offering self-steer, acceleration and braking on single-lane carriageways. Because what premium car would dare be revealed in this day and age without a Tesla-chasing autonomous mode?

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