The forthcoming Mercedes-AMG GT Black Series will offer "insane" performance, according to Mercedes-Benz CEO Ola Källenius - who has given his personal guarantee that Autocar readers will love it.

Due to be revealed next year before going on sale in 2028, the new supercar is a road-legal twin of the next-generation Mercedes-AMG GT3 racer, likely to be powered by a highly tuned version of the firm's new flat-plane-crank V8.

In its conception and positioning, the GT Black Series closest rival will be Toyota's new track-honed GR GT supercar.

Mercedes reserves the Black Series badge, first used in 2006 for an extreme iteration of the SLK 55 AMG, for its most hardcore performance road cars.

While it hasn't confirmed the engine or performance details, AMG has said the latest Black Series car will produce significantly more power and torque than the 603bhp and 627lb ft of the current GT 63 Pro.

Speaking exclusively to Autocar, Källenius said: "Sometimes you must allow the engineers to go crazy, and the next car like that is in the making."

Pressed for details, he added: "The next AMG Black Series will be insane, and it will be something completely different that nobody expects. And I can guarantee that Autocar readers will love it. You have my personal guarantee.

"I know I'm talking to a constituency that knows what they're talking about, and I have full confidence we won't disappoint."

While Källenius wouldn't give any further details of the project, he noted that the new flat-plane-crank V8 engine was a key part of its investment strategy in combustion technology, saying: "We're going to need that for years to come, especially for sports cars."

He revealed that he personally owns a V8 SL and so appreciates the appeal of such engines for enthusiasts.

The push to fit the mildly hybridised V8 into AMG models in place of plug-in hybrid powertrains is a notable change in strategy.

Källenius insisted the firm will continue to develop PHEV systems, which can be used to boost efficiency in some cars and power in others.

But he said there would still be demand for non-hybrids from people who "prefer the lower weight..."

He linked the spirit of the forthcoming GT Black Series to the AMG One hypercar, which essentially put the V6 turbo hybrid powertrain from Mercedes 2015 title-winning Formula 1 racer onto the road.

Källenius joked that "we should have been put in an asylum" for approving production of that car but added: "I'm very happy we did, because it will be one of those moments in time that a bunch of engineers received an impossible task and found a way to do it. For enthusiasts, that will be one of those milestones for decades to come."

You can read the full exclusive interview with Ola Källenius exclusively online on our Apple News+ channel. You can also read it in this week’s Autocar magazine, which is available on news stands or as a digital edition.