McLaren did indeed restrict the 675LT Coupe to 500 units. But people badgered the brass-hats at Woking to do a Spider. And McLaren figured two things. One, if they didn’t do it at the factory, aftermarket firms would oblige, by taking Coupes and hacking in the roof module from a 650S Spider. And two, McLaren couldn’t resist the trade of 500 extra units at £285,450 a pop. The limit is set at 500 because that’s how many McLaren figured it could sell without the residual values beginning to tail off. However rich these customers are, they don’t want their cars’ value to plummet. They didn’t get rich by being mugs, and it would make their friends laugh.Too few. They sold out in a very few weeks after the announcement last December.Nope. Anyway, don’t pretend you have £285,450 to hand.Wonderful. Just like the 675LT Coupe. Manically fast, but incredibly controllable and engaging. A full-on experience. A joy. And, here’s the point, an even greater thing in Spider form.Both the Spider, and the Coupe come to that, lose a lot of the sound insulation of the 650S. Much of the tub is bare. And the 675LT also has ultra-hard engine mounts, to get sharper response and a better feeling of connectedness. Plus the suspension bushes are stiff, and the tyres aggressive. All of which means a lot of road noise and tuneless engine grumble when you’re at a steady-speed cruise. The sort of driving we all have to do a lot of, even if on the way to a favourite road or track. McLaren’s own 650S is an absolutely terrific long-distance car. So for that matter is a Ferrari 488 GTB. The 675LT is sometimes the wrong kind of noisy. But in 675LT Spider, drop the roof and the problem goes away. It’s always the right kind of noisy. The harsh racket is replaced by the rush of the air through which you pass, and the epic vocalising of the 675bhp V8 and its tuned titanium exhaust.ot so I could tell. For a start the weight penalty is a mere 40kg versus the Coupe. And the strength is almost all in the lower tub, which survives the conversion intact. The roof isn’t really part of a McLaren’s structure, so it doesn’t suffer in the removal. The changes weren’t enough for even McLaren’s fastidious engineers to make any compensating adjustments to the springs or dampers.Even today’s top-echelon hypercars fail to make the 675LT look sluggish. How about 0-124mph in 8.2 seconds? (A Porsche 918 clocks 7.2.) The quick wittedness of the 675LT engine is almost enough to make you forget it’s a turbo – though its sheer punch doesn’t leave much doubt. The engine is vastly modified from the 650S unit, in search of response more than outright output figures. Its torque curve takes a long rise to a peak, not a wide plateau (Ferrari does the same, but McLaren revs higher, which matters). More revs give more urgency: an eruptive, narcotic, wanton rush for the red-line. It sounds, roof-down, fabulous. A multi-layered filling of the stave. The exhaust, an insanely expensive long-pipe lightweight titanium confection, is one reason the LT has a little more overhang than the 650S. So literalists won’t be upset at the Long Tail name. The transmission is recalibrated for even faster shifts when you wind up the calibration settings on the central console. Yet in normal mode it manages a handy combination of smoothness and promptness. I drove it in the wet. The combination of the engines’ predictable torque curve and the transmission’s helpfulness means you can short-shift and easily eke out all the rear tyres have to give.They have a lot to give. Traction is herculean but progressive. The car operates on a stratospheric plane, but elevates you with it. It’s sharp but not spiky. Meanwhile up front, the LT’s steering is magically alert, and feeds torrents of feel to your happy hands. The suspension for the LT is, like the engine, very much redeveloped over the 650S. The track is wider, demanding longer suspension arms that manage nevertheless to be lighter. Springs, dampers and active suspension calibration are all bespoke. The body is wider over the wheels. No stone was left unturned.The rear airbrake is far bigger than the 650S’s. Overall downforce is 40 percent greater, at least with the roof up. Some of the detailing makes you gasp. Front splitter endplates swerve air past the front wheels, after which it re-attaches to the side skirts and gets scooped into the bodywork ahead of the rear wheels, to meet a radiator. Hence, better cooling than the 650S without the weight of bigger rads.Well, I have ACTUAL NEWS here. McLaren’s people are now saying that LT will be their future hardcore brand. They make no attempt to deny that there could very well be an LT version of the 650S’s successor. And indeed of the 570S. Lighter, harder, a little more powerful, more engaging, more aerodynamically uncompromising. More track-happy, if you will. Probably they’ll also be made in limited numbers. So keep your eyes peeled for announcements over the next few years, and be prepared to open your PayPal account at very short notice indeed.