My mother-in-law has an 2003 S500 4-matic and since new she has complained about the car pulling and vibration in the wheel. When she took it in, the tech said it was fine and balanced the wheels. At around 20000 kms she noticed the outer edge of the front tires were badly worn. The dealership rotated the tires and gave the reason for the wearing was her driving aggressively and the weight of the car. After about 7000 more kms she brought the problem to my attention. I looked at the tires and drove the car. It pulled and there was a shimmying in the wheel. I felt it was an alignment problem. I spoke with the service manager at dealer 1 and after much debate he agreed to align the car and replace two tires free of charge. He did tell us that we can expect to replace tires every 20000 kms and have alignment done every 2 months. I couldn't believe my ears. We wanted to switch from the contenental tires to the michaline MXV4 so we paid the difference and told them to replace all four tires. After the work the car seemed to handle better. The car was taken to dealer 2 for routine maintenance after 4000 kms. This dealer said the car is pulling, the front tires are feathered and we should take it back to dealer 1 for alignment. We went to dealer 1 and they said the car is fine and they would not do anything. So we went back to dealer 2 and they agreed to do the alignment. They rotated the tires, made alignment adjustments and told us to come back after 2000 kms. After 2000 kms we brought the car back and the front tires were badly feathered. Now we have four brand new tires badly featherd and no answers. The service manager showed the tire manager and he said right away the car needs alignment, the service manager said alignment has been done already. This dealer has now agreed to do alignment again and also replace two tires which they claim michaline is covering under warrenty. That still leaves us with two badly damaged tires we paid for 7000 kms ago and no answers as to what is wrong with the car. They won't replace the back tires which if they hadn't rotated would still be fine and they said if this alignment doesn't solve the problem then there is nothing else they can do for us. This dealer also blames aggressive driving and the weight of the car as the reason for the tire damage. They also say that alignment needs to be done every two months and tires need to be replaced every 20000 kms. I think they're crazy if they expect me to belive this. My mother in law is not an aggressive driver and the dealers claim that no other s500's are comming in with this problem. I have contacted head office and they leave it in the hands of the service managers. What is wrong with this car?