I know brand is important, but don't forget to look at the whole car. I mean, mileage, general condition, car history etc...... For instance, look in the engine bay and look for "bent" frames. Body shops can fix the exterior but often neglect to fix the internal frames. Another tell tail signs are paint colors. Check door sills and frame and see if its not aligned. Is the undpinning of the car a different color that would hide bondo or body work. High mileage and low mileage? Condition of hoses and timing belts. You may have a nice MB on one hand that has either been driven by a house maid or a woman who has'nt changed the oil since they bought it. It may have been used as a service car. Drive it, drive it hard. See if anything breaks away. Check history whether it was a stolen and recovered car, totalled or damaged. You definitely do not want a lemon. Make sure they give you at least 1 year warranty. Good luck!