I have a SLS and love to drive it. I think it drives better than any car that I have ever owned. I have noticed the tire vibration problem between 50 and 70 mph, a little annoying, but guess I will just have to put up with it untill GM comes up with a fix or recall. The SLS offers a lot of comfort and sport in a luxury car. Sorry that they choose not to put the Cadillac Seville name on it. I have had a few to ask what make and model it is! Although the Cadillac emblem is unmistakable.
Oh my god!!! I just bought a 2000 with 55k on it and this has been driving me crazy. I'm going to try Michelins. Wish me luck.
Front end vibration between 60-70 can be fixed by replacing the Factory idler arm a "MOOG" (after market) Arm which absorbs the torque between the left and right drive wheels.
My 2005 DeVille suffered from a vibration that started at 39,000 miles. The dealer balanced the tires and then replaced the tires with no effect on the vibration. Then the dealer measured the play in the hubs (wheel bearing assemblies) and found three of them to be out of spec. They replaced those hubs and the car has been perfect since then.
I recently purchased a 2003 Seville STS. It is a great car, but also has a front end vibration problem. So far I have replaced all four tires with Michelin's, Installed two front brake rotors, and replaced the left front wheel bearing. I also had the wheels road-force balanced at the local Cadillac dealership. I still have the problem. I reading website comments, people state that tie rods, idler arms, and motor mounts have solved their problems. Also, Cadillac has a service bulletin that refers to redesigned lower control arms as a solution. I would appreciate any feedback on how to proceed in correcting this problem. There must be a logical trouble-shooting sequence to solving this problem. Also, given the number of complaints on this one problem, there must be a design error involved.