It's the noise that gets you first. The 911 GT3 R is a pretty raucous monster as it is, what with its sequential dog 'box and zero sound proofing between you and its howling flat six engine. But throw a flywheel into the mix, one that sits roughly six inches to the right of your backside and rotates at an astonishing 40,000rpm, and the sound this car makes becomes altogether more terrifying.
Gradually, as the two electric motors mounted over the front axle generate more and more energy from the brakes, and then send that energy back to the flywheel, a row of bright green Christmas tree lights begins to illuminate on the left side of the dash. When each of these is lit - there are about 10 of them - that's when you know the system is ready. That's when you sit there and wonder for a second what it will feel like to unleash another 160bhp, on top of the 480bhp that the flat six already produces up near its 8200rpm cut out.
It actually feels like you've hit some form of hyperspace button, because you don't so much as accelerate but appear at your destination a whole lot earlier than you thought possible. And it's a spooky sensation in the extreme, because the extra energy just seems to arrive out of nowhere. There's no impression of it being delivered in a crescendo; it's either there in full, or it's not, depending whether you've pulled the lever.
And on a track, of course, 6-8seconds is a long time to be at full power. In effect it means you are almost always able to call up extra power. Which leads us neatly into the single most impressive aspect of the GT3 R's hybrid power-train - the speed with which it can generate and redeploy its energy. All it takes, in fact, is one big stop from sixth to third gear, and that's enough energy to virtually recharge the system in full. So in effect what you are talking about is an extra 160bhp/120lb ft that's available pretty much all of the time.
On the downhill stretch you wouldn't use it, instead you'd allow it to fully recharge under brakes for Graham Hill so you could use it all the way along the bottom straight. Under brakes for Clearways you'd then get another recharge, meaning you could open it up out of Clearways and use it for most of the pit straight. There would be only one straight during the lap on which you couldn't use it, in other words, and that would be on a downhill section anyway.
Over a 24 hour race that advantage proved critical. The only reason the GT3 Rh didn't win the event outright on its maiden outing, in fact, was because a valve spring let go during the last hour, at which point it was in the lead. The hybrid system itself was faultless, in other words.
As the GT3 Rh's chief race engineer, Owen Hayes, said to me after I climbed out, looking somewhat dazed by the whole driving experience: "I regard the whole hybrid thing a bit like mobile phones from 20 years ago. Some people said they would never catch on, and look where they are now. For endurance racing in particular, that's exactly how I feel about hybrids."
Hybrids have arrived, and how.
So how does the GT3 Rh's hybrid system work?
The GT3 Rh generates its power by taking the natural energy generated under brakes, putting this through two 60kw electric generators, storing this energy in a flywheel, and then redeploying it through the generators (which act as motors when in reverse). The electric flywheel can produce 160bhp of continuous power once it has reached its 40,000rpm operating speed; and that's what takes time and sounds so dramatic to spool up from inside the car.
911 GT3 R hybrid Specification:
0-60mph: 3.1sec (approx)
Top speed: 191mph
Economy: 8mpg (approx)
CO2 emissions: n/a
Kerb weight: 1350kg
Engine layout: Flat six, 3996cc, petrol + two 60kw electric motors
Installation: Flat six rear, longitudinal; electric front, transverse
Torque: 440lb ft (approx)
Power to weight: 474bhp/tonne
Specific output: 160bhp/litre
Compression ratio: n/a
Gearbox 6-speed sequential dog
Fuel tank: 100 litres
Range: 180miles (approx)
Front suspension: Struts, coil springs, anti-roll bar
Rear suspension: Multi-link, coil springs. anti-roll bar
Brakes: 380mm ventilated steel discs (front); 355mm ventilated steel discs (rear)
Wheels: 18in forged alloy
Tyres: 27/65-18 front, 31/71-18 rear