With AMG, it's always all about the powertrain
This is the first time that AMG's new, normally aspirated, 518-hp, 6.2-liter V-8 engine, which began trickling into the Mercedes lineup two years ago, has been installed in the SL roadster. This also marks the debut of AMG's new 7-speed Speedshift transmission with comfort, sport, sport-plus, and manual modes, all of which are controlled but round buttons located to the left of the gearshifter. The significance of this transmission is that it uses a new wet start-up clutch rather than a traditional automatic's torque converter. AMG says that the car offers 30 percent faster shift times than the AMG 7G-tronic transmission. The transmission also blips for downshifts when it is in manual mode, just like in a Ferrari.
I played around with the four drive modes over the weekend and found that I liked sport-plus and manual best. In sport-plus, the shift times are plenty quick, the engine revs to redline in each gear, and off-the-line acceleration is lightning-fast. It was easy to lay a little rubber, too, although I have to admit that I drove conservatively all weekend, because the Monterey Peninsula was crawling with cops and I figured I was a magnet for them in this car. Manual mode is quite entertaining, too, but I always find myself forgetting that I'm in it, and end up lugging the engine at redline in first gear before remembering that I need to bang the gear lever sideways to upshift. Shift times lived up to AMG's billing, and the shift action itself is very crisp and direct.
Straight-up comfort mode is fine for freeway cruising, but when the transmission is simply in Drive, there is not enough oomph for passing. People who want instantaneous torque whenever they mash the accelerator might be a little disappointed in the SL63, as it doesn't offer the locomotive-like torque of the twin-turbocharged, V-12 SL65. No surprise, that; it's the same with all Mercedes 63 AMG models. But that's why AMG installed such a cool new transmission; you just have to learn to make it work for you. Trust me, there is nothing arduous about this learning process.
Is it a true sports car?
The SL63 AMG is certainly more than just a luxury roadster, and unlike some previous AMG efforts, its chassis tuning is as impressive as the powertrain. As part of the $24,275 "Launch Edition" options package, it boasts a specially tuned version of Mercedes-Benz's ABC (active body control) suspension system that keeps the car very flat when you throw it into a corner. When you set the suspension to sport mode, chassis responses become noticeably more taut, but ride comfort does not unduly suffer. The car has decent steering feel, even if it's not quite up to Porsche's standard. The SL63 is really a very livable, grand touring super-roadster, one that someone who's tired of sitting on the waiting list for a Ferrari F430 Spider could quite enjoy.