Brakes
Pad life, rotor replacement, fluid service and what a brake job should cost.
Brake maintenance is mostly wear replacement, and wear rates vary more with how you drive than with what you drive. The same pads that last 70,000 miles on a highway commuter can be finished at 25,000 miles in city stop-and-go traffic or towing in the mountains.
The part owners underestimate is brake fluid. It absorbs moisture from the air through the hoses and reservoir vent, and moisture lowers its boiling point. That does nothing on a normal drive and everything on a long descent. Brake fluid service is cheap and almost universally deferred.