Try to get one with a manual gearbox if you can as the auto boxes are known for failing and can be costly to fix. As mentioned above, these can rust a fair bit. Main places to look are all 4 arches, front of bonnet around grills, and above the rear number plate on the boot. Also get a mileage check done (VOSA, etc) as there are a few clocked E46's out there. Apart from the above they are brilliant cars.