If you add in a few extra variables it would be better.
_car = _this select 0
_guy = _this select 1
_velx = _car velocity select 0
_vely = _cal velocity select 1
_car setvelocity [_velx,_vely,_rate]
This way you can set the hydraulics going as you drive along. Also reducing the _rate gives you a nicer effect, though less funny.