I am not sure what the minimum thickness is for an ML is, but my car for example is in the 20.4 - 19.4mm region, You need calipers to measure the different areas on a rotor.

MB OEM rotors are actually cheap, they never get turned only replaced.

Mercedes brake pads are easy to replace, you can get some idea from the "DIY" section on the top of these pages. Having the proper torque specs and brake pad paste helps.

Checkout "STARTUNED MAGAZINE" and other links at

wait for an ML owner to reply, also MB uses a few different style brakes all easy to work on, you won't need any SPECIAL tools.