The SLS is REAR wheel drive. REAR. Dunno where the FWD stuff came from. My post was referring to the XTS, which is a different car*.
The SLS is just a long-wheelbase version of the US-market STS. I still can't figure out why anyone would want a turbo four when you can get an LY7 or LLT in the SLS delivering the same or better power a lot more smoothly.
Here in the US, the bottom-end engine option is GM's spectacular 3.6 V6 (LY7 EFI variant for early models, LLT direct injection model now...same motor making 315hp in Camaro and CTS). Midrange motor's a 315hp Northstar, and the top-end (STS-V) engine is the supercharged 470hp, 440 ft-lb Northstar. ALL of those engines make the ecoboost 2 liter in the T-series look like a joke.
*The reason the XTS came up at all is that Caddy will be replacing both the DTS and STS with it for ~2013. It will be FWD and V6 powered, but still large (DTS sized). Think Lincoln MKS. It's a fail move, unless they release something else in that size range with RWD and a V8. While DTS buyers might be happy with FWD, STS buyers won't be. And yes, the STS sold underwhelmingly compared to CTS and DTS. But that's only because Cadillac barely advertised it, never mentioned it, and sized the CTS too closely to it. None of that changes the fact that, as a "premium" sport-lux brand, Cadillac REQUIRES a big rear-driver. You can't maintain a BMW-alternative image selling FWD cars with cylinder shortages (I'm looking at you ACURA AND LINCOLN!).
Imagine Infiniti replacing the M56 with a VQ35-powered front-driver. It's just unfathomable. I have NO IDEA what GM is thinking.
Oh, and the XTS isn't just a bad idea performance-wise, either. It's proportioned like a beached whale, and will almost certainly weigh in like one, too.

The damn car is BACKWARD. The rear overhang could house the homeless population of Denver, but out front we've got compactcaritis in droves with the A-pillar and fenders. The car isn't just proportioned like the new Taurus...it even has that a**-dimple crap going on behind the rear wheel arches. And that C-pillar needs reigning in in the worst way. No rear decklid but 17 miles of car behind the edge of the roof. Who came up with this crap? Mail them off to 90s Chrysler and have them pitch it as "Cab Forward." It'll start a revolution.
The fact that Caddy even released that picture to the public makes me want to burn my Cadillac wreath hat and never mention them again. Not even the godly amazingness of the CTS-V wagon makes up for that vast expanse of fail.
I can understand Lincoln doing the faildance with V6s and FWD...the LS was an aberration and the rest of the lineup never was BMW-worthy (or even MB worthy) before the MKS anyway. But I've been a Caddy guy since I can remember, and Caddy actually has something GOOD going now. "The New Standard of the World" is NOT FRONT WHEEL DRIVE. I'm offended. The XTS
offends me.