When you let off the fuel on the 300d the high compression does indeed slow the car. You let off the gas on an auto 4 speed overdrive gas 6 banger and it does not slow at all. I'm not talking about the jake brake on the big rigs which does help to slow them down, I am talking about the 3x compression the 300d has over the 8 to 1 gas. I can drive in traffic and by watching what is going on several cars ahead almost never touch the brakes. The newer benzes that have overdrive 5 and 6 speeds may not have the same effect, but the older 4 speeds which are geared like a gas three speed, do. What it comes down to is the far superior brakes on the German cars. My wifes van has front disk, rear drum, and the front disks pads are smaller than whats on my car by a good 1/3. With factory pads and good tires it will stop on a dime.