By John Simister
Mercedes - with a little help from McLaren - goes after Ferrari and Porsche with its fastest production car ever, and 4car's John Simister is one of the very first to try it. So what's it like at 200mph?
We have just nudged an indicated 300km/h - that's 186mph - on the Mercedes-Benz SLR McLaren's luminous speedometer. Should I keep my right foot planted? It's tempting, because the acceleration shows no sign of abating; the talk is that someone else has seen 340km/h today, which is 211mph. And surely the speedo of a car with such a distinguished engineering pedigree must be reasonably accurate...
'Comfortably over 200mph'. That's all the SLR project people will say at the moment, not least because the final certification isn't complete. Anyway, the straight of the test track near Barcelona is running out, the car in front is getting close and there's a banked bend to tackle. 'You shouldn't go round the banking at more than 200km/h in lane four,' the test track woman said earlier, 'otherwise you'll drift up into lane five, which we don't have.''
But then we weren't supposed to drive faster than 250km/h or 155mph on the straight, either, because Michelin hasn't yet approved its new SLR tyres for higher speeds and, besides, the track is baking hot. Not to worry; it felt fine on the banking at 230km/h.
This is one potent car. Its creators still won't say what their acceleration target times were, but the SLR is apparently whole seconds ahead of the estimate for the 0-100mph run. Nor will they be pinned down on the power ('over 600bhp') and torque ('700 to 800Nm' - or between 516 and 590lb ft).
What makes the SLR a breed apart from the other members of the latest supercar wave, though, is the way it delivers that power and what effect it has on its ability to tackle corners. Supercars, on the whole, are mid-engined because that's the way racing cars have been for the past four decades. But this one is front-engined; you can tell just by looking at its extra-long bonnet and the way the cabin is squashed up towards the back.
OK, make that front-mid-engined. The engine sits behind the front axle line, like it did in a vintage car, almost eating into the cabin. Ahead of the engine is a long intake duct, complete with a colossal air filter, which begins at the three-pointed star. "Every styling detail has a function on this car," says Andreas Montmann, the SLR's product manager. Either side of this, behind the other air intakes, are radiators for engine cooling, air-con, oil, the power steering (it gets very hot) and the two heat exchangers, one per bank, for the supercharger's charge-cooling system.
That charge-cooling is how this engine gets its extra urge over that of the SL55 AMG. The SLR's engine is also an AMG production, derived from the existing 24-valve, 5439cc, supercharged V8; but now with an all-new dry-sump lubrication. It drives through a five-speed automatic transmission taken from the Maybach (it's big enough to handle all that torque) but reprogrammed with AMG Speedshift R. I'll explain shortly.
The SLR's carbonfibre monococque shell is four times stiffer than that of any Mercedes saloon, designed and made in ways not previously attempted with carbonfibre. "We use a new computer-controlled manufacturing process, which allows us to make the shells more quickly," says McLaren's managing director and ex-Fiat/Alfa product guru Anthony Sheriff, "This speed and the low weight could be the future for mass production."
First, the structure. Central to McLaren designer Gordon Murray's concept is how the SLR behaves in a crash. The central monococque includes the 'roof spider': one moulding which comprises the sills, the door and windscreen apertures and the roof frame. It's possibly the biggest moulding of its complexity yet created, and it forms a vital energy path in a crash - which is why there won't be an open-topped SLR.
Unlike the all-carbonfibre Porsche Carrera GT, though, the SLR has a hefty pair of triangulated cast-aluminium front frames to hold the engine and the front suspension in place. These are bolted to the front bulkhead, rather like the front subframe of a Jaguar E-Type. Ahead of these is more carbonfibre, in the form of a pair of stepped cones designed to telescope on impact. It's much like a Formula One car's front end, but duplicated. "It's very unlikely the monococque would get damaged in a frontal impact," says Montmann. "If you had a crash big enough to do that, you'd be dead in a steel-bodied car."
That will be a comforting thought when I first slip into the red leather driving seat of silver SLR prototype number MP3. Before that, though, there's the exterior to drool over. My first view of the SLR is through the door of the test track's workshop, head-on front, that low, pointed nose with Alfa-style offset number plate flanked by the giant ears formed by the upwards-and-outwards-opening doors. Behind the front wheels are giant air-exit vents like those of a Gullwing SL, below these vents are a pair, on each side, of exhaust pipes echoing those of the SLR race car in which Stirling Moss and Denis Jenkinson won the 1955 Mille Miglia.
Are these pipes legal? Apparently so; they are among the many changes made to the SLR design since the Vision SLR concept car. Every panel is slightly different, and the tail is much higher for aerodynamic reasons. The styling is very obviously Mercedes-led with strong SL connotations, but the zebra-stripes of camouflage hide the impact while these prototypes finish their development. September's Frankfurt show will reveal the finished article, and the first production car will leave the McLaren factory in Woking at the turn of the year.
This prototype has 18-inch wheels shod with 245/40 front tyres and 295/35 rears. They're a five-spoke design and the lightest of the three options, the others being 10-spoke 18-inchers and 11-spoke 19-inch items. All are by OZ and, perhaps surprisingly, Michelin's 19-inch tyre gives the best wet grip. "We've just finished developing it," says Chris Goodwin, McLaren's chief tester, "along with the final steering calibrations."
He explains what a joy it is to work with such a stiff structure: "You can feel a 2Nm change in spring rates straight away, while in a normal car you could change the rate by 20Nm and not notice." He's covered 10,000km around the Nurburgring's Nordschleife (north loop), and had a lot of fun running with the Porsche Carrera GTs being tested at the same time. The two cars proved to have similar lap times, but when conditions turned bad the SLRs were quicker. "Even Walter Rohrl says the Carrera GT is hard to drive," Goodwin chuckles, "and they wrote off two."
The SLRs were quicker because they're designed to be easier to drive: an ultimate GT, not a racetrack fugitive. It has the full gamut of ABS anti-lock brakes, ESP (electronic stability program) and Brake Assist because it's a Mercedes. (It's a German car, project director Christian Fruh contends, even though it's built in Britain and partly designed here.) But there's nothing trick about the steering, which has normal hydraulic power assistance with no Servotronic control, nor the double-wishbone suspension which has regular Bilstein gas dampers and no rear anti-roll bar. Easy, transparent, predictable reactions were the aim.
I'm in the seat. The door needs a hard pull to latch it shut, but production cars will have easier, soft-touch closing. A machined aluminium seat pictogram moves my leather bucket with its air-conditioned seatback vents; I can adjust reach, height and tilt but the backrest is fixed. Tall people may lack head- and legroom in this cosy cabin, which is a surprising failing.
All the soft trim apart from the seats is swathed in a brushed nylon camouflage, but enough is escaping to show shiny carbonfibre, more leather and Bose speakers beneath. I flip up a cover on the gear selector and press the start button. The V8 erupts into cultured but malevolent life, blipping instantly to the accelerator and eager to burst out of its cage. A rotary knob on the facia will allow me to choose between auto comfort, auto sport and manual gearshift modes; another selects one of three manual shift speeds, progressively trading smoothness for acceleration. That's AMG's Speedshift R.
We start in auto sport and smoke off to a lane-change manoeuvre. The getaway is instant; there's no auto 'box slurring here. This feels a wide car at first, but it dives into the flick precisely and powers out with easy, accurate control.
Now a long, fast bend. Lots of power pushes the tail out, but it's ultra-progressive and doesn't threaten to get out of hand. The bend leads to a box formed by cones, and I'm going too quickly to reach that destination if I carry on at this speed. So I brake and steer; there's no drama, just a tidy tightening of the line, steering staying in focus, complete control.
Next a slalom, through which this hefty dragster spears cleanly, tidily, with ultra-precise steering and hardly any discernible tyre scrub. It's all so easy; no sudden spins, no plough-on understeer, heroics for all. I repeat the above three more times. Then it's on to the high-speed circuit.
I can tell you that the sound at mega-speeds is surprisingly loud (not that anyone should complain much about such an animal V8's beat 'n' crackle - like an SL55's played through your biggest speakers). The steering initially feels worryingly light at high speeds, too. You must convince yourself just how connected it still is.
And then there are the carbon-ceramic composite brakes, with eight-piston front calipers and massive stopping power. Unlike the Enzo's or Carrera GT's discs, these are controlled by Mercedes' Sensotronic brake-by-wire system. That makes it easy to unleash huge stopping forces without much pedal pressure, and Goodwin admits there's still some fine-tuning to do on the pedal response.
Not that the discs do all the work. There's also an air brake, a pop-up rear flap as seen, in much larger guise, on that Mille Miglia car. It rises automatically by 10 degrees beyond 56mph to improve stability, but the driver can press a button to increase this to 30 degrees if s/he senses the need for more rear downforce. If you brake hard from high speeds it pops up to 45 degrees, the extra downforce helping the rear brakes to contribute more to the stopping power, and stays up until you drop back below 56mph so the aerodynamics don't suddenly change.
After four high-speed laps, Sheriff by my side and pleasingly relaxed, I'm on a high. They're so easy, these big SLR speeds, and I just want to go faster and faster and hold it at the 7000rpm rev limit in fifth gear. Will it do that? If it does, that would be about 217mph. We'll just have to wait and see what the official specifications say at Frankfurt.
Meanwhile Mercedes has plenty of advance orders, including five from one buyer who wants one for each of his worldwide houses. The owners won't be in such an exclusive club as those of a Carrera GT or an Enzo, though, because the plan is to build 500 SLRs a year for five to seven years, depending on demand. The cars will get serviced at Maybach dealerships, which will have the correct lifting ramps to fit the carbonfibre chassis.
Buyers will be able to see their cars being built on-line, too, or visit the all-glass factory. The handover promises to be quite lavish, with Armageddon-style flashbacks of the car's build process before the finished SLR emerges into view. One final thought. The likely price is about £250,000. Compared with its recent rivals, that's almost a bargain.
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