[Bingo]

You are not getting the vehicle's ID dude you just defined it.

Look at /uselock you'll see on top new id= and so on.

EDIT*

Quote:

new id = Car_GetID(GetPlayerVehicleID(playerid));

Chnage id to vehicleid and add it on top of your tow command and make sure to read the full command, I am on tablet sorry.