I was driving my car home that had 29000 miles from the dealership when I felt something like a flat tire. The when I pulled over, all tires were good, now I heard scraping. Couldn't drive anymore, noone was at dealership, next day I called they said happens all the time, make sure e-brake is released, feeling stupid, I checked but my rear diff was shot. Said known to happen at times. After doing some thinking and talking to other dealerships about what is done at the 30 k maint., and how long a diff. would hold out with no fluid, I concluded they forgot to refill the diff with fluid. They denied, but fixed no questions asked because of the extended warranty.