An older car with low mileage can look like the obvious bargain beside a newer car that has been driven more. The odometer gives you a clean number to compare. Unfortunately, it cannot tell you which car will fit your next few years of ownership better.
I would not choose either one from age and mileage alone. I would want to know what shape each car is in, what work is approaching, and how much driving I expect to do. Low mileage deserves attention. It does not deserve a blank check.
Suppose you are comparing a ten-year-old car with 45,000 miles against a five-year-old car with 90,000 miles, both at a price you can afford. It is tempting to describe the first as barely used and the second as nearly worn out. Neither description has been earned yet. They are two starting points for an inspection.
Tires offer a clear example. NHTSA explains that tires age through changes in their materials, with storage, use and environmental conditions affecting the process. Plenty of tread does not establish that an old tire remains suitable for service. Follow the tire and vehicle manufacturers' guidance rather than treating low mileage as a reason to ignore age.
For the rest of the car, have the technician compare its condition and service history with the manufacturer's maintenance requirements. If time-based work is due, include it in the purchase budget. A car does not owe you several years of inexpensive ownership because someone else drove it less than you expected.
Be equally careful with the story attached to the newer car. “All highway miles” may be true, but a seller's description is not a condition report. It does not settle whether the car needs tires, brakes or other work now. Evaluate those items directly, just as you would on the older vehicle.
The useful comparison is the amount needed to buy each car and bring it to the condition you expect. Have any identified work priced separately. If you cannot afford the older car's immediate needs after paying its low-mileage premium, it is not the affordable choice for you.
Add your own miles before choosing
Now give the example a future. At 20,000 miles a year, three years of ownership would put the older car at about 105,000 miles and the newer one at about 150,000. At 5,000 miles a year, those figures would be about 60,000 and 105,000. The same two cars serve quite different plans.
Those calculations do not predict a breakdown or a resale price. They help you decide how much weight to give remaining mileage, age, and the features you will live with. Someone driving several hours each day may value the newer car's actual comfort and equipment differently from someone making short local trips. Compare the equipment on the two vehicles rather than assuming every newer model has the features you want.
A useful offer also leaves room for ownership after delivery. Spending the entire budget to secure the lowest odometer reading leaves no room to deal with the car you bought. Paying less for the higher-mileage choice is not much help either if known work immediately consumes the difference.
I would take a well-supported condition report and a workable ownership budget over a winning number in an online filter. Let the mileage help narrow the search. Let the actual cars decide the purchase.