Following in the tracks of the Porsche Cayenne Turbo and Mercedes ML63 AMG, the SRT-8 is insanely fast. As a package it can’t match costly rivals, but the flagship Grand Cherokee is sure to get you noticed.

In the days of rising fuel prices, heavier tax for big polluters and anti-4x4 lobbying, you’d expect all makers to focus on green SUVs. Everyone, that is, except Jeep.

While rivals are working on efficient new diesels and hybrids, engineers at the US off-road giant have been busy shoehorning their most powerful petrol V8 into the Grand Cherokee to create a supercar-chasing 4x4. The SRT-8 takes its name from Chrysler’s Street and Racing Technology performance arm, and is 25 per cent more powerful than a standard Grand Cherokee. The 6.1-litre V8 produces 420bhp and 569Nm of torque, with impressive results.

Use all the power and the 0-60mph sprint takes exactly five seconds, while top speed is just over 150mph. Needless to say, achieving these figures has caused Jeep to set aside any off-road pretensions to produce its first dedicated tarmac model. In normal driving conditions, 90 per cent of the power is fed to the rear wheels, while the tuned suspension and dampers allow the car to ride 25mm closer to the road.

It’s in a straight line that the power is most usable, but the Jeep is surprisingly capable in corners, too. Body roll is controlled and there’s barely any understeer when turning into a bend. At £40,585, the SRT-8 is hardly cheap, but some might consider it a bargain given it can outperform rivals costing nearly twice as much. What’s more, the aggressive bodykit means it’s a real head-turner. Buyers will still need deep pockets, though, as the SRT-8 manages only 17.2mpg in the combined cycle and 388g/km CO2 emissions mean tax bills will be huge for company buyers.

It might be Jeep’s least capable mud-plugger, but the SRT-8 is undoubtedly the firm’s finest handling model ever. Just don’t expect it to save the planet.