Porsche Cayenne Turbo E-Hybrid is firm's most powerful ICE car

The new drivetrain, which will also be available in the third-generation Panamera, receives the same electric components as the Cayenne E-Hybrid, including a 174bhp electric motor and a 25.9kWh lithium ion battery. That will enable an electric range of 51 miles, which CEOs picking their next company car will be delighted about.

Providing the meat of the power is the latest version of Porsche’s twin-turbocharged 4.0-litre V8 petrol engine, which now runs a mono-scroll turbocharger with an electric wastegate in place of the twin-scroll turbocharger used previously, among other changes.

The wholesale increase in power and torque pitches the most powerful of Porsche’s plug-in hybrid-powered Cayenne models into direct competition with the BMW XM Label Red, whose petrol-electric drivetrain kicks out 738bhp and 738lb ft.

We got to drive a prototype of the Cayenne Coupé with the GT package ahead of a planned unveiling at the Munich motor show next week, and performance is nothing short of scintillating.

The new plug-in hybrid drivetrain is hugely muscular, providing rabid step-off and fervent in-gear acceleration. The combination of electric motor and petrol engine power provides absorbing linearity and prodigiously muscular qualities to the delivery. There is great urgency under load in lower gears and effortless cruising on a more relaxed throttle in taller ratios. It is also terrifically vocal, with a deep-throated roar to the titanium exhaust in more sporting driving modes.

It is all handled by an eight-speed torque-converter automatic gearbox, with shift paddles mounted on the steering wheel, and a fully variable four-wheel drive system.

The flagship Cayenne’s handling is equally as compelling as its sheer straight-line performance. There is precision and purpose to the heavily weighted steering, which benefits from a 0.45deg increase in the camber of the front wheels and a rear-steer function. The GT package also brings a 10mm reduction in the ride height over standard versions of the new petrol-electric Cayenne. 

The suspension combines dual-chamber air springs with an electromechanical anti-roll stabilisation system to provide outstanding body control and a great deal of grip. The torque-vectoring rear differential ensures a distinctly rear-biased feel yet momentous drive out of tight corners. It is not subtle, but it is hugely capable, delivering a level of agility and outright dynamic appeal that no 2700kg-plus SUV really has any right to possess.

Relax the driving mode to Comfort, and the most powerful of Porsche’s new plug-in hybrid Cayenne models is agreeable enough, given its performance potential. The ride with the GT package is still firm, mind. However, quick-acting variable damping and excellent wheel control provide it with sufficient absorption and compliance to ensure the UK’s upcoming alternative to the Turbo GT doesn’t get too unruly over nasty ruts and ridges. 

Further features of the GT package include Porsche’s carbon-ceramic brakes and a lightweight carbonfibre-reinforced plastic roof panel.

There’s no doubting its dynamic ability. It builds on the appeal of the already hugely capable Turbo GT with drivetrain electrification that ramps up the performance, as well as changes to the chassis to ensure it retains similarly captivating handling despite its added weight.

A definitive verdict will come when we get to drive the production version later this year, but based on this early prototype, it’s going to be a very fast and rather special kind of SUV indeed.