In engineering terms the motor industry is standing on the edge of a precipice. The ground is already crumbling away beneath its weight and soon it will give way altogether. But, for once, this is a cliff we’re going to enjoy falling off. The ground is all the pointless mass accumulated by cars over the past 20 years and it’s giving way now because car manufacturers have realised that their traditional, lazy and easy route to additional sales – adding power and feature content – now lead nowhere.
The buzzword of the next 10 years is going to be ‘lightweight’. Now cars are taxed punitively on their CO2 emissions and what easy reductions were available through improved electronics have already been made, there’s no other way for car manufacturers to make their machines affordable to run than cut their weight.
This, of course, is brilliant news because lightness feeds on itself. Take weight out of a car’s body and structure and suddenly you can get the same performance from a smaller and therefore lighter engine. For the same reason you can save weight from a car’s brakes, suspension, wheels, tyres… the list is long. And while the biggest winners will be small and affordable cars, the ripples will extend to the fastest, largest and most expensive machinery on the market as it responds to the news that, for the first time in a long time, big is no longer beautiful.
The new Mercedes-Benz SL seen here makes the point startlingly well. Let us say you’ve been driving the AMG version of the outgoing model these past few years. You’ve probably been having a rather good time. But now is the time to trade it in so your natural instinct is to look at the new AMG SL, yours for a trifling £110,735. Natural, but wrong.
What if, instead, you compared it to the SL500, costing more than £27,000 less? At first it seems a less than appealing prospect: not least because the power output of the new SL500 is ‘just’ 429bhp, compared to the monstrous 518bhp of your old AMG. Now look a little more closely: the old AMG weighs almost two tonnes, the new SL500 less than 1800kg. Now factor in the new car’s twin turbos which actually deliver far more torque than the old SL63 motor. Do the maths and you’d find their power-to-weight ratios are quite similar, look at the numbers and you’ll find Mercedes quotes identical acceleration times for both cars. But the biggest difference of all comes when you drive the car, more of which in a minute.
It is simple to explain how all that weight has been lost: essentially Mercedes now builds the SL from aluminium rather than steel and while you’d expect a lighter car with a smaller engine to use less fuel, I did have to look twice before confirming the new SL500 will go over half as far again on a gallon of unleaded as the old SL63. That’s 30.7mpg compared to 20 dead.
But now we get to the really good bit. The SL500 may be merely the equal of the SL63 in a straight line, but when the entire dynamic package is considered, it’s in a different league. It seems odd to be comparing an AMG product unfavourably to an off-the-peg Benz but that’s the what we can expect when a company such as Mercedes tackles weight loss.
Indeed, and I say this carefully, this is the first generation of SL that can start to stand comparison to the original. No, it is nothing like as far ahead of its time or, indeed, anything else on the road as was the 300SL in 1954; but after years of weight gain, of becoming ever more the long-distance tourer and ever less the honed and incisive driving weapon, the tide has turned.
I discovered this on one of my favourite roads local to where I live in the Wye Valley. It’s a tricky stretch, wide but full of sudden surface changes, unreliable cambers, tightening radii and different gradients. I only tackled it at speed because it was required as part of the evaluation, not because I particularly wanted to: large convertibles have an almost unbroken record of feeling terrible when hustled along that particular stretch of road. And this wasn’t even the sporting version.
I cannot remember when a car last so exceeded my expectations on that route. I knew it would be quick but this SL500, the direct descendant of the car once driven by Bobby Ewing, was suggesting I drive not as a professional duty but for the sheer hell of it. It wasn’t that I was unable to resist its charms: I never even tried. This large convertible Mercedes without an AMG badge to its name kept me thoroughly entertained from end to end. The secret of that particular road is that a car needs some compliance in its suspension to breathe just a little to absorb its many imperfections. It did it perfectly.
If there is a downside to the SL’s new attitude to the open road, I failed to find it. So far as I can tell it rides just as well as any previous SL, but because there’s now proper legroom for tall drivers, it’s far more comfortable. And when you raise the roof you really cannot detect any deficiency either in terms of refinement or structural rigidity compared to an equivalent coupé.
What it promises is a convincing answer to a conundrum that’s existed ever since the car became sufficiently reliable to make sense as a means of travelling great distances. Clearly you want to get there as quietly and comfortably as possible, but once you’ve arrived in the south of France, Italy or wherever your fancy takes you, it is an entirely different kind of car you seek. This is what the SL provides.
Or at least this SL. There are two others on sale, the aforementioned new SL63 AMG with 529bhp and an SL350 with a 301bhp, 3.5-litre V6, both of which feel less complete than the mid-range 500. The problem with the 350 is the same that has plagued all junior SLs over the years: the ones with the little engines just don’t have the same appeal and it applies whether you’re comparing a 190SL to an original 300SL or a modern SL350 to an SL500. These days an SL without eight cylinders just doesn’t feel, sound or perform as it should. The power deficit is one thing, but the relative lack of torque is the killer: the SL350 requires almost double the revs to produce barely more than half the torque of the SL500. The result is an entirely different driving dynamic that might sit comfortably with retirees living in Palm Springs, but here offers an emasculated experience.
But the SL500 doesn’t just make the SL350 look inadequate, it calls into question the wisdom of spending all that extra money on the AMG. The new SL63 is pulverisingly powerful, but after an admitted brief acquaintance I felt the driving experience only marginally enhanced, and not by enough to justify the substantially additional outlay.
So the 500 it is. This really is the most remarkable machine, the most desirable SL since the original and as good an example of what happens when a serious manufacturer gets serious about weight reduction as you’ll currently find.
Engine: 4.7 litres, 8 cylinders, petrol, twin turbo
Top Speed: 155mph (limited)
Power: 429bhp at 5250rpm
Fuel/CO2: 30.7mpg, 214g/km