The McLaren BP23 will be the fastest McLaren ever. Woking has now confirmed that the next car in the Ultimate Series line-up will have a top speed of at least 243mph, outstripping the maximum achieved by the F1 back in 1998.

It won’t, however, get involved with the top speed war currently being waged by Bugatti, Koenigsegg and Hennessey. “Absolute top speed is not the point,” McLaren CEO Mike Flewitt says, “but it will be very, very, very, very quick, by far the fastest car McLaren has ever made. Beyond that, we want to sell a car that can do what it can do straight out of the showroom. If it had a set of tyres that can do 300mph, they’d be horrible to use – damn near solid. I want to deliver a package that’s drivable. What it won’t do is set any lap times because it doesn’t have a whole load of downforce”.

BP23 (it stands for Bepoke Prototype two, three seat), will be revealed before the end of the year. McLaren has already said only 106 of the central driving position cars (the same number as original F1s) will be built, but further details are harder to tease out.

McLaren hasn’t yet made statements on power or engine, but Flewitt did – perhaps inadvertently – reveal it will use the twin turbo V8. “There’s quite a lot of development in the V8. It’ll be with us into the middle of the 2020s. The lowest power is about 430 in the GT4, and we’ve done 1000bhp with hybridization in the P1 GTR. I’m not allowed to tell you what BP23 will be, but there’s a fair amount of stretch in that engine”.

We already know it will be a hybrid (I speculated on total power when I drove the BP23 prototype), but will it be 4WD? Flewitt wouldn’t be drawn: “There are arguments for and against. You get better traction and control, and to take 0-100kmh times down then it’s appealing - 4WD would get it down to the low 2s. And regeneration of the battery from the front wheels is good. But the downsides are weight, what it does to brake and steering feel…”

We know it’ll go into production at the end of next year, and will carry a name rather than a number. Given it’s the second pillar of the Ultimate Series alongside the track-orientated Senna, that’s hardly a surprise. P2 and F2 are off the agenda, then…

“One of the fun things about the Ultimate series,” continues Flewitt, “is that it lets you head off in a direction to an absolute extreme and you can compromise other things. This is a car you want to drive 800 miles a day in. It’s comfortable, relaxed and phenomenally quick.”

So where will McLaren go to do big speed? They can’t use VW’s Ehra-Lessien test track as they did for the F1, as that’s now Bugatti’s stomping ground. Over to Andy Palmer, vehicle line director for the Ultimate Series. “Obviously there are roads, such as the one Koenigsegg used, but running on a road, from a safety perspective, gives us a few issues. Bonneville might be possible, but salt isn’t a great surface and we want to anchor this car on the tarmac. All I can say is we’re evaluating a couple of places.”