I have a 2013 250 CDI SLK with 12k miles on the clock which I bought recently and have an intermittent problem. When accelerating, not aggressively, just normal it sounds like the car is going over rumble strips, from the drivers side I think, and more so when turning left. It is of course under warranty but its sods law that if I take it in it will be fine. Can anyone give me a clue as to what it could be. many thanks