Have them check it bumper to bumper... every squeek every niggle. Be a pain in the @ss. Check the oil sender unit on the sump, have them check the oilpump aswell. Radiator expansion tanks, Control arms and bushes, front and rear, viscous clutch on fan, aircon system, and belt tensioners... THe above are all things I had to replace 7000km out of MP on my e46 325i. Cost a pretty penny, and 10000km later a steptronic box rebuild...