I bought the car with 22,000 miles and now have 65,000 miles almost a year later. The only repair I've made (under warranty) was some front end work. The diesel has returned 35 MPG total average in predominantly highway driving (150 miles/day). With the exception of the front end work, the vehicle has been flawless, even the electronics (which is surprising). I've owned six Mercedes before, mostly diesels, and wholeheartedly recommend the brand, and particularly their diesels.
Fuel economy and comfort at high speeds. The torque is also outstanding.
The only complaint is the braking system which seems harsh at times. However, I understand that this was remedied is subsequent models. A minor irritation is the necessity at times having to adjust the heating controls. The paint finish seems to have a slight orange peel effect, but not serious.