Even with a dead battery and no vacuum you can always open the trunk with the key if you have locked the car previously with central locking. By why lock it while you tow it?
On a side note, towing a car with auto trans should be at max 30-35 mph and not for a long trip. Better then to remove the drive axle at the flex plate.
Or maybe I completely misunderstood your post?!
On a side note, towing a car with auto trans should be at max 30-35 mph and not for a long trip. Better then to remove the drive axle at the flex plate.
Or maybe I completely misunderstood your post?!