LA MOTOR SHOW: Mercedes-Benz smooths SL

The folding metal roof of Mercedes-Benz’s SL roadster used to be symptomatic of its problems. Other sports and big touring cars have passing the sixth generation of Benz’s venerable SL roadster by as it waited, stationary, to raise or lower its roof, just as they’ve done in the sales race.

It’s also lost some identity. The rise of the SLS and the SLS Roadster over at sister company AMG means, that for the first time, SL hasn’t sat at the apex of the Mercedes-Benz two-door tree.

Now, though, a mid-life facelift means it will have more power, more torque, better economy, a better ride, some handling and styling tweaks and, finally, a roof that can be opened and closed on the move.

Mercedes-Benz insists the roof can now make its way up or down at anything up to 40km/h. It’s not the 50km/h most are claiming these days, but it’s better than sitting still.

On sale in Europe and the US from April next year, the upgraded SL will also get the kooky active body control suspension that leans into corners like a motorbike (well, the first five degrees anyway), along with a nine-speed automatic transmission.

The Mercedes-Benz and two AMG versions will launch at the same time, with the AMGs boasting both biturbo V8 and V12 powertrains to sit atop the V6 and V8 engines in the standard range.

The cheapest of SL will now be the SL 400, with a 270kW turbocharged V6 petrol engine, while the SL 65 caps the family with the arrogance of 463kW from its bi-turbo 6.0-litre V12.

It might be just 3.0-litres, but the SL 400’s powerplant delivers 500Nm from 1800-4500rpm, promising flexibility in real-world conditions and still delivering a sub-five second sprint to 100km/h. It also gives a solid 45kW power jump on the old SL350 and its torque is up a convincing 130Nm.

It reaches the benchmark in 4.9sec on its way to a limited top speed of 250km/h. The same speed limit applies to all the new SLs, though the AMGs can be optioned to move that to 300km/h.

Significantly, the V6 400 leads the way on fuel economy; posting 7.7L/100km on the NEDC Combined driving cycle.

The V8 SL 500 is the traditional Benz family flagship, with the 4.7-litre twin-turbo V8 moving up to give 700Nm from 1800-3500rpm, which gives way to 335kW that hits its stride at 5250rpm and hangs on to 6000. Its power gains are more modest than those of the mainstream family members, with the torque figure staying the same, but the power rising 15kW.

The sprint time is slashed to 4.3sec but it costs a bit in fuel to get there, with the V8 slurping up 9.0L/100km.

It doesn’t seem to use a lot more fuel to jump from the SL 500’s V8 to the SL 63’s 5.5-litre biturbo version, because the NEDC figure is just 9.8L/100km.

But if the SL 500’s output data looks tasty, the SL 63’s looks like the stuff you need to make people drool. It crunches out 900Nm from 2250-3750rpm, and then the power curve hits its peak at 5500rpm. And when it hits, it hits with 430kW of thump, pushing it to 100km/h in 4.1sec.

You pay a lot more for the SL 65’s twin-turbo 6.0-litre V12 to get to 100km/h just a tenth of a second faster than the SL 63 – a stat that speaks loudly of the longitudinal limitations of the rubber as much as anything else.

The V12 gets 1000Nm at 2300rpm, holds it across a 2000rpm band and then keeps pushing beyond the 5500rpm power peak of 460kW.

It’s a more costly thing to fill, though, officially claiming 11.9L/100km but good luck matching that in the real world. (As if its owners much care…)

All that extra torque means the AMG versions of the SL keep using the in-house seven-speed automatic transmission, which is essentially a strengthened and developed version of Benz’s old seven-speed, with a sharper clutch pack stuck on one end.

The outgoing R231 model faced criticism for the wooliness and indirectness of its steering and the lack of cohesion in its handling. Benz hopes to move on from that with developments in its optional active damping. It uses those computer-controlled dampers to lean in to corners, and it’s a system that works well in the S-Class Coupe, in particular, so there is promise for the SL.

The AMG units have completely different suspension kinematics, a mechanically locking differential and slightly different geometry, highlighted by a sharp rise in negative camber on all four wheels.

It has the usual Benz array of electronically managed safety features, including Active Brake Assist, which uses its radar (at both ends) to detect potential collisions, then warns the driver of the danger and then takes over and brakes by itself if its warning is being ignored. It is the Lewis Hamilton braking option.

The visual differences are largely up front, with a new face, a new grille, a new bonnet, new splitter and air intakes, new front quarter panels and new LED headlights.

It’s being pitched as more grand tourer than ever before, with Mercedes emphasizing words like “elegance” and “relaxed”, so if it’s harder-core bend eating you’re after, perhaps the upcoming GT S Roadster will be a better fit.

“The SL is an all-season vehicle that is fully suited for daily use, but above all it is a dream car for those special moments as a coupe,” Benz’s director of sales and marketing, Ola Källenius, explained.

“Whatever its owner desires, it fulfills the expectations with technical perfection.”

Well, it might have been edging perfection some years ago, but the current model has been less than loved in the market.

Of its predecessors, the third-generation R107 arrived in 1972 and stayed on for an astonishing 17 years, while the R129 kept selling steadily from 1989 to 2001, a span of 12 years.

The first SL, the W198, ran from 1955 to 1963, while its successor, the W113, also managed a nine-year lifespan.

Even the SL immediately before this one, the R230, ran from 2001 to 2008 before its facelift eked out another four years of sales life, giving it a full-cycle 11 years on the market.

There seems little chance of the R231 making it that far, though. When it is replaced next year, it will have lasted just four years after it was launched at the Detroit motor show in January 2012.

Still, it gets advances that could only be dreamed of in past SLs, including the Magic Sky Control, which dims the roof glass from transparent to a dark blue at the push of a button. Highlighting the two-year development pause on the outgoing SL, the Magic Sky Control system was optional in the SLK back in 2011.