McLaren informs us that the side windows on the new, 986bhp P1 GTR are built from motorsport specification polycarbonate, with a sliding 'ticket window' on the driver's side the only access to the outside world.

Handy, then, should you wish to collect your medication on the move. And you'll likely need much medication after driving the new McLaren P1 GTR, because it's quite, quite bonkers.

Here it is then, ahead of its official Geneva Motor Show debut, in a new track video alongside the F1 GTR. Yep, what you're thinking right now is correct.

You'll know that this new P1 GTR is a track-only special, like Ferrari's FXXK, with a tweaked version of that 3.8-litre twin-turbo V8 pushing out 789bhp, while an additional 197bhp is made available via that electric motor. That's a combined 986bhp. That's a lot of oomph.

McLaren tells us "features within the powertrain designed specifically for public highway use have been removed to reduce weight." Yet more weight has been shed thanks to those lightweight side windows, carbon fibre roof panels and engine bay cover. Overall, it's 50kg lighter than the road-going P1.

Then there's the 80mm wider front track, the 50mm lower ride height, 19-inch motorsport alloys, an aero blade across the lower front, and one of the most ludicrous, astonishing and downright excellent rear wings we've seen for some time. Just look at the thing.

It's fixed, sits more than 400mm above the rear bodywork, and helps to increase downforce: talk is made of 660kg at 150mph. It's mounted on carbon fibre pylons - yes, pylons - and caps off an aggressive rear end featuring larger tailpipes that save 6.5kg over the road-going P1.

The livery? It's inspired by the Harrods-sponsored McLaren F1 racer, one of seven that competed at Le Mans in 1995, one of which was driven to the podium by official TG hero Mr Derek Bell.

As many as 30 cars could be built, offered only to the 375 owners of the P1. So, y'know, it'll be expensive. And exclusive. Now, watch it go up against the F1...