The mechanism itself deserves attention, too. Rather than being hydraulic, its uses eight electric motors to silently raise or retract the roof at vehicle speeds of up to 31mph (versus 18mph for the old 650S Spider). It's also light, and with no strengthening required for the tub, the Spider weighs only around 50kg more than the coupé. Its dry weight is a mere 1332kg.
It means that, in terms of performance, there's almost nothing between coupé and Spider. Both hit 62mph in 2.9sec and only by 124mph, which arrives after 7.9sec, does the coupé pull out – and even then, only a nominal tenth. The drawback for Spider owners is that their car is limited to a mere 202mph when the roof is stowed away and head room endless, but even if you live among the German autobahns, this is a technicality, and with the roof in place, you'll manage the full 212mph, just like the coupé.
What's it like?
With the roof up, the driving experience is indistinguishable from that of the coupé.
Make no mistake: this a major – and possibly unique – achievement and a big selling point for the 720S Spider. No comparable open-air machine has the same steering precision or immediate body control, which combine to make for awe-inspiring direction changes. In less than perfect conditions, you'll get a little understeer through slower corners, but the Spider generally swoops around bends with phenomenal accuracy, security and front-end feel. No change there, then.
New to the Spider is a rear windscreen that drops down into the firewall between the engine bay and the cabin, roof still in situ, which is something you can’t do on the coupé. It’s a lovely bit of theatre. You not only get properly acquainted with McLaren’s heavily turbocharged 4.0-litre V8 – which is, if nothing else, brutally loud near an 8500rpm redline and more flambouyant than ever in its distinctively pneumatic, breathy manner – but also the lake of heat that collects above the carbon engine cover washes into the cabin with every forceful application of the brakes. You literally bathe in this engine.
Sophisticated? Not especially, but for a car that generally struggles to engage its driver on an emotional level, it does the trick.
And then you lower the roof. From here on, the 720S Spider ceases to simply feel frighteningly fast and begins to seem incomprehensively so. For the full effect, you wind all the windows down and slip the powertrain into Track mode, at which point the short exhaust issues an uncomfortably loud explosion with every near-instantaneous downshift from the seven-speed dual-clutch transmission. The sense of chaos created by 710bhp and 568lb ft, the whirlwind within the cabin and the speed at which the scenery slips by is accompanied by calm, clinical handling. It's a strange juxtaposition, but an enjoyable one.