E420 has fixed calipers. That means the caliper is bolted, and does not move. The pads follow the rotor.

The floating calipers are bolted, but they can moved back and forth to follow imperfections in the rotor.

However floating calipers dont stop very fast, they are found on early model 300Es.

If you prefer to have those brakes, I can trade you.

__________________
Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.