Very simple. Its just a 4*4 sprite with a checkerboard patern.
Put 2 imagepoints (skidmarks01 and skidmarks02) at the end of your car sprite.
every tick+If Car is moving -> spawn checkerboard at Car(imagepoint) skidmarks02
Same for the second one.
And don´t forget a line to erase them
If checkerboard-sprite is on screen (revert) -> destroy
Cheers man. ^^
BTW, i don´t know if its the server right now, but your game will not load. O.o