IMMENDINGEN, Germany – After dominating the Autobahn with the GT 63 S E Performance, we took a detour into the lush, undulating south German countryside. It wasn’t just to mix things up. There, lurking in the forest just outside the tiny town of Immendingen, was a Mercedes testing facility and the brief chance to sample the 2025 Mercedes-AMG SL 63 S E Performance.
And by brief, we mean it – two half-hour stints on twisty rural roads around the facility as well as some slow-speed village cruising. No Autobahn, and no high-speed blasts at the “Prüf- und Technologiezentrum,” either. It wasn’t a lot of time, but the good news is that the SL 63 S E Performance is basically a convertible GT 63.
The powertrain is identical, including the 4.0-liter twin-turbo V8, nine-speed automatic, 4Matic+ all-wheel-drive and a rear-mounted motor fed by a 6.1-kilowatt battery pack and sent through a two-speed rear gearbox. The SL 63 S E Performance has the same 805 horsepower and 1,047 pound-feet of torque as the GT version, plus the same estimated 8 miles of electric range in European testing. It’s only a tenth of a second slower to 60 mph (2.8 seconds) and 3 mph slower in top speed (196 mph).
The similarities don’t stop there. The two cars share the same width and wheelbase, are nearly the same length (the SL is shorter by a little more than half an inch), and the interiors are basically the same. Rear axle steering, carbon ceramic brakes and the trick Active Ride Control suspension are similarly all standard. The SL is basically a convertible GT with a different front fascia and a center screen that can tilt to reduce glare with the top down.
So mostly everything we said about the GT 63 also applies to the SL. But there are indeed some differences. The biggest, well, aside from that cloth roof, is the suspension tuning. Though it also has the Active Ride Control suspension (among a variety of wildly complex elements, the adaptive dampers are interlinked hydraulically), the tuning is a bit softer across the board than the GT. It’s not a dramatic difference – the SL is darn-near as fleet-footed on the street as the GT – but it’s enough to imply that the SL is meant to be a bit more relaxed. It sacrifices that little bit of response for a little less harshness. This character shift also helps make the somewhat disconnected steering much more forgivable.
So what we have is the GT, but just a tad more chill. There may be merit to that for some, but we’re ultimately left with a less intense version of a car we concluded wasn’t intense enough given its prodigious power. It almost seems wasted, even more so in the SL. The 577-horsepower, non-hybrid SL 63 offers more than enough wallop, making the 805-hp S E Performance overkill, and not necessarily in a fun, Hellcat sort of way. A boisterous AMG V8 will sound just as growly with the top down whether or not it has an electric motor up its backside.
Now, what the non-hybrid can’t provide, is peaceful, silent, top-down cruising. As fun as hearing that V8 echo through the German hills was, it was equally as lovely to let those pipes go quiet and just enjoy the wind rustling past as the sun set. The sleepy little villages we silently passed through probably didn’t mind, either. Also, as we previously covered, the motor’s 200 horsepower is plenty for toodling around, even up to highway speeds.
But then we ran into the same problem as before: You can barely go anywhere on electric power. In no time at all, you’ll have drained that dinky all-electric range, and you’ll be needing to run the V8 to recharge the pack. That’s also assuming you charged it up before hand.
So just like the GT, we’re left wondering about the powertrain’s fitness for the purpose. In the GT, it seemed like the car was bestowed with enormous power, but not made sporty enough to properly take advantage of it. In the case of the SL, it’s more that it seems like Mercedes didn’t go far enough in electrifying it. The electric function is highly appealing, but the range so meager as to be nearly pointless for just weekend outings, never mind daily driving. And since it’s not a maximum-attack sports car, it would’ve been nice to see Mercedes focus more on range and capacity, instead of rapid discharging and power. For that matter, it leaves us pining for a fully electric SL.
There is something we know about the SL that we don’t about the GT: price. The base price for the SL 63 S E Performance will start at $208,150. That’s a pretty similar price jump between the SL 55 and the SL 63, and for a much bigger power increase. So at least in terms of power per dollar, it’s not a terrible deal.
If you want the most SL, the S E Performance is unquestionably the choice. And it’s still a beautiful, comfortable and fast machine, one that’s a pretty reasonable price considering what it adds on paper. But what it adds in experience is more questionable. Its V8-only siblings offer nearly all the gas-powered experience, while its own electrified benefits are negligible. It’s conflicted, and as result, so are we.
