Holy cats. The Real Steering version has two kinds of grass. Normal grass doesn't slow down the car, but deeper grass does. This is missing from the Intuitive/Directional version.
You can see where the deeper grass is if you bring it up in jzIntv's debugger. Run until you get the playfield on screen. Hit F4, and then type these commands:
p3938 AA p3939 55 p393A AA p393B 55 p393C AA p393D 55 p393E AA p393F 55 r
You'll see most, but not all of the grass highlights in a checkerboard pattern. This is 'tall grass', and it'll slow your car down. Try driving on these areas in the "Intuitive/Directional" version, and you'll see your car doesn't slow down. At least, that appears to be the case.