What's it like?

To activate the P85D's full potential, you press a button on the huge central touchscreen marked (and I'm serious about this) 'Insane'. And that's pretty much how it feels. Tesla's acceleration test track was a well-abused mixture of greasy cold asphalt and coarse gravel, but the P85D still managed to deliver a level of acceleration that would be difficult for anything else to match in the same conditions. It's the initial punch that does it - the kind of uncompromising shove from 0-30mph that comes with the torque characteristics of electric motors in general, now mixed with four-wheel drive.

What's missing, of course, is any sort of soundtrack. There's none of the sense of occasion that you get with a 458 attempting similar feats - or anything approaching the aural pleasure that can be delivered by a hard-worked AMG V8. Instead, you hear a distant whoosh as the twin motors kick in, accompanied by - and this is perhaps oddest of all - the sounds of the tyres themselves grabbing hold of the surface beneath them (on a dry road, presumably, you'll not even hear that).

Once you're up and running, there's even less standing in the way of the P85D's colossal torque; you'll need to be well beyond the UK speed limit before you'd detect any discernible reduction in the car's ability to gain momentum.

Try to carry too much speed into a corner and the P85D will simply understeer; behave yourself and the nose tucks in with more conviction than it does on the 85 (itself not a bad steer, by any measure). Regardless of how hard you're pushing, it stays admirably flat in corners - and there was enough compliance to dial out the worst road surface imperfections on Tesla's Norwegian test route.

There's still not much communication, though; you get three weights of steering to play with, but despite this, and regardless of the P85D's ability to thrill and delight every time the traffic lights go green, this is not a car that makes you feel truly connected to what the tyres are doing. In that respect, at least, the P85D feels like one of the family - a slightly more planted and considerably quicker stablemate to the 85 and 60.

The same can be said for refinement, really, because the large alloy wheels still create a fair amount of road roar once you're above 40mph. It's by no means noisy aboard the P85D, but nor is it as silent as you may expect a fully electric vehicle to be.

The cabin remains a clever bit of packaging, with room for five adults and potentially two further children in rear-facing seats in the boot. The luggage capacity is still enormous, with space under the bonnet and in the traditional boot totalling almost 1800 litres. The finish on materials is of a remarkably high standard compared with any other American car - although a few elements are half a notch behind the best European executive models when you get to a close-up inspection.

The showpiece of the cabin is still the Model S's gargantuan centre screen, a 17in behemoth of a touchscreen through which you control the majority of the vehicle functions, let alone infotainment or navigation. It's still a bit worrying to see the system redrawing chunks of map as it struggles to keep up with sheer amount of real estate it has at its disposal, and there are occasions when you'll wish they'd just fitted a permanent button - Volvo's new system on the XC90 does a better job of fast-tracking you to regularly used functions - but in the most part it's a triumph.