Are you serious? When you are on the highway, you are rarely driving in a straight line for a mile, so the diff is working all the time.
BTW, I put a full size front in my trunk today, along with a lug wrench, scissor jack and wheel chocks.
There's not much room left over for luggage. Basically, the wheel blocks access to what little volume is left over.
But, now I'm ready for a road trip!
