I play on PC, and whenever I try to use a drill on a vehicle, the vehicle it is attached to sinks into the ground. The drill I have been using has a strength of three. Everything else ranges from begin attached to a tractor on glacio to being attached to a large rover on sylva, and I dont really see any pattern. However, this is rendering my drill useless(which took me a long time to get). I almost lost an RTG because the trailer it was attached to sunk into the ground: it took me 15 minutes to find in a cave two levels below the surface and 30 minutes to get it out of there.