I use a Kracher power washer on my silver C240, our silver SLK230, gunmetal Range Rover, and black metallic Porsche 996. I have no problems with scratching the paint. First I spray a chemical solution on the cars using a mist spray, then I blast it off. I repeat this with a shampoo conditioner. Finally I spray a rinse agent, which I rinse off using the mist spray.

Be very careful on plastic parts or where there are stone chips: the most powerful spray will lift the paint where it has already been chipped (I took the paint off the door mirror of the 996 this way).

These machines are fine for regular or quick washing. They will not get a filthy car gleaming, however. I find I still have to do the wheels by hand on all except the SLK.

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JJ Rodger
2013 G350 Bluetec
1999 SL 500
1993 E300 diesel T
1990 190