Check all fluids, power steering, transmission, diff, brake, coolant, tire pressures. I always jack up each wheel, yank the wheel back and forth, up and down, looking for play. See if any shocks are leaking or worn. Open all doors, put car through all the gears with foot on brake, listening for pops, cracks, clunks, and such. Check all the bulbs, including license plate and trunk light, glove box lights, and so on. Just give it a good combing, its a great idea because it gives you an idea of the road ahead, and wether your future comprises of repair bills in the hundreds, or thousands.
Trust me, it goes quick, I got my 240D for $1200 thinking id put in another $200 and be golden..... NOT!!!!! an additional $1200 later, and now Im approching golden, Injector rebuild, all new filters / fluids, brake rotors / pads, cruise switch, bulbs, fog lights, alternator, starter, battery, UCA bushings, Lower ball joints, sway bar bushings, shocks...... you get the idea. Basically I am just helping you prepare. Mercedes are GREAT cars, and sometime the first few months can be hell, but I can assure you, your Stutgart designed masterpiece will, and I mean WILL return the favor for your hard work. With a glistening, gleaming, upper eschlon car that many only dream of owning.