[FireFox_]

pawn Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
    if(strcmp(cmdtext, "/carhop", true) == 0)
    {
      if(IsPlayerInAnyVehicle(playerid))
      {
        new Float:X, Float:Y, Float:Z;
            GetVehicleVelocity(GetPlayerVehicleID(playerid), X,Y,Z);
            SetVehicleVelocity(GetPlayerVehicleID(playerid), X,Y,Z+10);
            return 1;
        }

    }
    else
    {
      SendClientMessage(playerid, 0xFFFFF, "You are not in a vehicle");
        return 1;
    }
    return 0;
}

The scrip hasent been tested. Hope it works