Mercedes’ SL gets a new face for 2008 but there’s far more to the SL63 AMG than simple cosmetic surgery. As the name suggests, the big Benz sports car finally adopts the naturally aspirated V8 that’s already available in other AMG cars, which means that the old supercharged ‘55’ V8 is no more.
So what are the headline numbers for the SL63 AMG?
The atmo V8’s 800cc swept volume advantage reclaims the power lost by not having a whacking great blower forcing charge into the combustion chambers. Power is up from 510bhp to 518bhp making this the most powerful V8-engined Mercedes around (the twin turbo V12 SL65 is in another league altogether with 604bhp).
But it wasn’t the power that amazed when you mashed the throttle in a 55, it was the torque. The old engine churned out 531lb ft between 2600rpm and 4000rpm, but this one makes do with 464lb ft that doesn’t peak until 5200rpm. The new car, like the old, is limited to 155mph but the 0-62mph sprint now takes 4.6sec, a tenth longer.
So the SL63 AMG is a step backward?
Not really. The old SL55 was a bit of hot rod, a car subsumed by its mighty engine. Huge fun of course, but the SL63 is much more balanced machine. It’s still incredibly quick in a straight line but you have to work the engine harder to extract that grunt so you actually spend more time enjoying the chassis than you did before.
The 6.2-litre V8 (Merc calls it a 6.3 for old time’s sake) isn’t a screamer like BMW’s V10. It’s quite linear in its delivery, there’s no one point where it takes off and goes crazy. But because the meat of the torque is developed further up the rev range, the SL63 has better traction coming out of corners and the ESP light spends less of its time blinking at you like a lighthouse. It still sounds incredible, like four road menders’ drills but blueprinted and running on Avgas, and there’s now one of those pointless launch control functions thanks to the fiendishly clever new gearbox.
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What’s so clever about the SL63 AMG’s new gearbox?
While everybody is rushing down the dual-clutch sequential-manual route, Mercedes has taken a different path. It reasoned that semi-auto ’boxes spend most of their time in full automatic mode, which is precisely when they are at their least impressive. A traditional epicylcic automatic gearbox provides much smoother gearchanges and is more compact – re-engineering the floorpan of existing cars to accommodate a new gearbox is an expensive business.
But the torque converters they use rely on fluid pressure to connect engine to gearbox and are only locked up solid part of the time. This, and the weight of the torque converter, hurts throttle response and efficiency. So Mercedes got clutch experts Sachs to add a wet-plate clutch to its existing seven-speed gearbox. A dry clutch would have been even lighter and more efficient but wouldn’t have been able to dissipate the heat generated when transmitting the V8’s twist to the wheels.
On the whole it works very well. Only a very slight judder when creeping in traffic gives any clue to this being anything but a normal automatic. And left in D – which, let’s face it, is where most automatics and DSGs spend their time – it slips between ratios as seamlessly as any other Mercedes without a clutch pedal. But attempt to add any juice and you can feel the extra response. The V8 feels light and eager to rev and there’s none of the slurring you get when coming on the power with many autos. Occasionally you get the odd uncultured jolt as different ratios are selected and sometimes you don’t get the gears the instant you select them (an AMG insider blames the cheap steering wheel switches), but this is an impressive attempt to marry auto and manual transmissions. For now only the SL63 gets this box (the SL65 is too torquey) but you can bet that it will find its way into more humble machinery over the next couple of years.
So what else is new?
Like all new SLs, the 63 receives a new nose to keep the seven-year old design fresh. It fairly ruins the lines of the non-AMG models but Mercedes counters that with cars such as the new C-class out-pouting the supposed range topper, something had to be done to pump up the demure SL. Fortunately it works better on the AMG cars where the fascia is balanced by new side gills and a diffuser thing at the back (complete with crappy fake mesh moulding).
Inside, the cabin is tidied up and, while it would have been too expensive to include the proper modern Comand system in the centre console of such an old car, the new interface is certainly easier to use. The SL’s age is also the reason why neither night vision or the Pre-Safe Brake option that puts the anchors on automatically when it detects a collision, is offered.
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Any mechanical changes to the rest of the SL range?
Continental Europe gets the option of a new entry-level 280SL powered by a 3.0-litre V6 with 231bhp that does 0-62mph in 7.8sec. It costs around £3000 less than the SL350 but won’t be coming to the UK. The SL350 receives the uprated 3.5-litre V6 recently fitted to the SLK. With 316bhp and 266lb ft of torque it’s as powerful as the 500 was a couple of years ago, hits 62mph in just 6.2sec, manages 28.5mpg and promises to be the pick of the non-AMG models.
Verdict
When the SL first hit the streets at the beginning of this decade, it had a pretty easy life. There was no Aston Vantage or DB9, no Audi R8 and no Bentley Continental. You either saved a few pennies and bought a 911 or splashed out double that on a proper supercar like the Ferrari 360.
But even with all that competition, the SL, and the SL63 in particular, is an incredibly alluring proposition. No it doesn’t provide that same quality of interaction you’d get in something like a 911 GT3, but it seems to have every other base covered. It is satisfying to drive hard – it’s fast, sounds illegally naughty, handles its mass incredibly well and is now a more complete performance package than the old SL55 was.
Yet for the 90 per cent of the time when you’re not in maximum attack mode, it slips perfectly into luxury GT mode. And the folding hardtop’s ability to make the SL two cars in one really hasn’t been matched by anyone in the class.