Top models of Bentley SUV will probably have the W12 engine. This is an artist's rendering.

Bentley CEO Wolfgang Durheimer says the company's long-awaited plug-in hybrid will use technology borrowed from other brands in the VW group.

He told Car and Driver at the recent Detroit auto show that Bentley didn't need its own hybrid system as a “matter of differentiation”.

“For us, differentiation is styling, appearance, prestige, craftsmanship, luxury,” he said. “For us, hybrid tech is a 'need-to-have' and it is perfectly appropriate for other brands, such as Audi and Porsche, to take the development lead.”

Which makes sense; those brands not only have bigger R&D budgets, they've also got a lot invested in hybrid technology already. If there is one thing Durheimer has learned at Bentley, it is not to re-invent the wheel.

He confirmed that the logical combustion component for the plug-in Bentley would be Audi's new twin-turbo four-litre V8 - already installed in the new Continental GT - with a platter-shaped electric motor/generator sandwiched between it and the transmission.

But he pointed out that the older W12 engine is quite short for a six-litre lump, and that it would be feasible to fit in a motor behind that as well.

Durheimer has also made plain that the electric motor will not be a BMW-style 'mild hybrid' add-on; he wants an electric-only range of at least 25km.

It's unlikely, however, that we will see the plug-in powertrain made available in current Bentley models; it will more likely debut in the next generation, including the still-to-be-confirmed Bentley SUV.

Durheimer admits that the VW board has yet to give the project the green light, but that's not stopping him; he knows exactly what he wants.

“The design process is already quite advanced,” he told Car and Driver. “The more time I have to investigate the situation, the more feedback I get from the market and from customers, the more convinced I am that this is Bentley's big growth opportunity for markets such as Russia, China, and, of course, the US.

And it's not going to be a little crossover - not from the company that was once famous for building what Ettore Bugatti referred to (not without admiration) as “the world's fastest lorries”.

“It will not be a Hummer,” said Durheimer, “but it will be on the large side.”

He pointed out that it would have to be equally comfortable to drive and to be driven in.

“We will need to have a lot of space in the back; we need to have a comfort zone, good air conditioning in the back, and everything you need to be transported in the back.”

If it's going to be that big, it'll probably have the W12 engine in the top models, but we'd expect to see the new V8 and a V8 hybrid set-up as well.

We'll let you know when the VW board makes up its mind, even though Durheimer seems to think it's a done deal.