[DRIFT_HUNTER]

pawn Код:

CMD:engine(playerid, params[])
{
    if(GetPlayerState(playerid) != PLAYER_STATE_DRIVER) return 1;
    new variables[7], vehicleid = GetPlayerVehicleID(playerid);
    GetVehicleParamsEx(vehicleid, variables[0], variables[1], variables[2], variables[3], variables[4], variables[5], variables[6]);
    if(variables[0] != VEHICLE_PARAMS_ON)
    {
        SetVehicleParamsEx(vehicleid, VEHICLE_PARAMS_ON, variables[1], variables[2], variables[3], variables[4], variables[5], variables[6]);
    }
    else
    {
        SetVehicleParamsEx(vehicleid, VEHICLE_PARAMS_OFF, variables[1], variables[2], variables[3], variables[4], variables[5], variables[6]);
    }
    return 1;
}

Next time use WIKI to read all about function
Vehicle parameters have 3 states

#define VEHICLE_PARAMS_UNSET -1
#define VEHICLE_PARAMS_OFF 0
#define VEHICLE_PARAMS_ON 1