My regular commute is only 1.75 miles and nearly all down hill on the way to the office.
Sometimes when I have to go to my NJ office I will do a bike-train-bike commute. Total pedaling mileage each way is about 18 round trip. Have not done that much this year. Still, my Subaru just turned 3 in the middle of July. Just went over 7,700 miles this weekend.