The 620R is built around the firm’s carbonfibre Monocell II tub. In that respect, it’s unlike the 720S and the latest Ultimate Series cars (which use the bigger, stiffer Monocage tub) but like the McLaren GT and, fairly obviously, the 570S. Like all modern McLaren road cars thus far, it has a twin-turbocharged V8 between the driver and the rear axle line. But from this point on, the differences between this end-of-the-line special and the rest of the Sports Series portfolio are many, various and significant.
While the 570S GT4 car’s 3.8-litre ‘M838TE’ engine is limited by strict competition regulations to an output of just 430bhp, it’s uncorked in the 620R to hitherto unprecedented levels. In this application, it makes 611bhp at 7250rpm and 457lb ft between 3500rpm and 6500rpm.
This uplift in output comes courtesy of reworked ECU and turbocharger management and makes the 620R the most powerful version of McLaren’s lower-level model family of this generation. It does, however, leave it some way behind key rivals, both front- and rear-engined, for outright firepower.
A seven-speed dual-clutch automatic gearbox transmits that power to the road, as do centre-lock forged alloy wheels of staggered sizes and specially developed Pirelli P Zero Trofeo R tyres. To give a genuine race car experience, McLaren also offers a set of racing slicks for track use as an option. We were offered the opportunity to fit these to our test car, but the rules of the Autocar road test dictate road-legal rubber is used throughout. Carbon-ceramic discs, with vacuum pump and brake booster technology derived from the Senna, help haul the 620R to a stop.
Suspension hardware has also been carried over from the GT4 car. The 620R makes use of the same lightweight, two-way manually adjustable coil-over dampers, which have 32 settings for bump and rebound. Meanwhile, the front and rear wishbones – shared with the 600LT and 720S – and uprights are fashioned from aluminium, while the spring rates and anti-roll bars are considerably stiffer than they are on either a 570S or a 600LT. Stainless steel suspension top mounts replace the regular rubber ones for sharper steering response and better feel.
The car’s massive, adjustable rear wing, along with the aggressive front splitter, bumper and bonnet, have been adapted from those used on the GT4 car to meet road car regulations.