For accident repair, ideally a mercedes collision center putting a car on a lift will find the truth.
No matter what, car should be point on lift for inspection
Drive as many examples of the particular model you are interested in as possible, learn the sound and feel of the car by testing as many examples as possible.
1) listen to car at start up, check tail pipe emisson at first start up
2) find out where car is parked check for fluid leaks on ground
3) check fluid levels, power steering
4) feel transmission engage in all gears at rest
5) check all electrics
6) check for heat and air conditioning
7) rev car to 2000rpm and feather gas pedal approx 200rpm under and over, listen for any piston knock in engine.
8) warm up car, drive five miles, accelerate hard from rest, then test hard acceleration -kick down- from 15mph, try some other higher speeds, check for gear engagement, stumble.
9) listen for wind noise when driving
Open doors, trunk lid and hood, look at the sheet metal and paint in jambs and channels, no creases, no paint tape lines.
Check paint finish in engine bay.
Lift up floor mats, and check interior and trunk floor for dampness.
Pay close attention to car at bumper height all the way around, feel and visually check for perfection.
Usa a kitchen magnet with tissue underneath to check for sheet metal in likely damage areas.
Look for original windshield, manufacturer and decal in lower passenger corner.
Check all four tires for same model, date and wear rate
Check all service records with mileage, no service records, no buy
Mercedes can do a VIN check on a vehicle, hopefully dealer will peform this for you. Relates all Mercedes dealer work with mileage
Professionals can make a poor paint job or poor interior look good for sale.
Don't buy any car that has been in North Carolina, or in flood regions.
Know which MB engines are head gasket leakers
Consider a new Mercedes C230 Coupe, BMW Mini,