Does mileage matter more than age when selling a car?

Both matter, but mileage typically has more direct impact because it correlates with wear on mechanical components. A five-year-old car with 30,000 miles will generally command more than a five-year-old car with 100,000 miles. That said, age matters for parts availability and technology obsolescence. Anything above 100,000 miles or significantly below average mileage for the car's age will move the offer noticeably in most buyer pricing models.