You need to use the miliamp stting on your meter. The normal draw on your car should be around 40 to 50 miliamps after all the control units have shut down. On this car you can have a 500 miliamp draw for up to about an hour after turning the car off, so you need to allow for that to see what the actual draw is. Several things that are prone to cause problems are the antenna and the cd player. Also be sure to have the trunk light turned off during this test.
Mercedes Benz Master Tech