The basics are comparable to the nearly four-times cheaper McLaren 720S... if significantly revised. The carbon fibre monocoque is uprated with a new double-walled rear crash structure – no need for a roll cage if it races, claims McLaren – and the 4.0-litre twin-turbo V8 gains 79bhp and 22lb ft, for a total of 789bhp and 590lb ft. Its suspension is hydraulically interlinked, like the 720S, but lowers in the Race mode we’re testing, like the P1 hypercar.
Crucially, weight also drops 85kg to a lightest dry weight of 1,198kg. Everything has been scrutinised to get to that figure, but the carbon exterior panels are particularly impressive: they weigh just 60kg combined. Huge vents channel air to the uprated engine and spoilers and splitters squash the Senna into the ground with a claimed 800kg of downforce at 155mph. Put it all together and you get 0-62mph in 2.8 seconds, 0-124mph in 6.8 and lap times that are, says a McLaren insider, comparable to the slick-shod, non-road-legal McLaren P1 GTR. Wow.
If the stats intimidate, the Senna soothes nerves on a sighting lap in dry conditions. The race seats are deeply supportive but highly comfortable, the low-set driving position is perfect, and there’s no racecar claustrophobia to this cockpit, partly due to door glass that wraps over your head and the unusual optional glass sections in the lower doors. The steering is light enough to make the Senna feel wieldy, if weighty and accurate enough to define the smallest input, gears slip by almost unnoticed, and somehow this engine feels less boosty than other McLarens, perhaps because it’s lugging less mass. It’s an easy car to drive at seven-tenths.
But the Senna is still an all-consuming experience to drive as fast as you can. Flatten the accelerator and there’s such a rush of speed accompanied by a rather industrial cacophony that you’re inclined to shift gears before the blue light ignites on the dash. But hold out for 7250rpm and the rate of acceleration as you close in on the redline is ferocious, and it makes braking as late as you dare particularly intense simply because everything is happening so quickly.