Still, I don't think it makes sense to claim that adding miles to your driving is a way to save money. You haven't claimed it, but it seems like you're hinting it. I'm happy to learn I'm wrong about that.

AAA's calculus seems silly to me since it is based on the replace-every-five-years plan. It's a silly plan. Certainly those fixed costs are high, but it's a choice one would make, and not a rational one in almost every case. And no wonder you bring up depreciation. Depreciation never bothered me, since I keep a car until it is nearly worthless. I get value out of my cars by using them. Selling them is a terrible way to make or even preserve money. For someone like me, a car depreciates by the mile far more than by the year.

I'll put it another way. If you have a trip to take -- outside of commuting -- which could be done easily in a car or on a bike (or on foot), there is no economic reason in favor of driving the car. Adding miles does not yield more money. So whatever the marginal cost of a mile is in a car, you save that much money by not driving it.