Do you feel it or hear it? Any droning type noises/sensations? The reason I ask is because many late model MB's experience torque converter lock-up problems. I've had several clients who have described this as a shimmy or vibration. Another thing I see a lot of is bent wheels. Apparently it doesn't take much to damage MB wheels. Usually bent wheels result in a rotational "thumping" type of complaint. I see lots of this on the newer models with 17" or 18" wheels. Let us know what happens.