How do you determine "highway miles" when evaluating a vehicle?

Unless an owner tracked their mileage usage and you accept their claims, there's no way to determine highway miles from city miles. It basically boils down to comparing the miles shown on the odometer to the condition of the car. You really have to crawl under the car/truck, lay on your back with a good flash light, and inspect the frame, brake/fuel lines, rust, wear patterns on tires, but all these are secondary to the condition of the engine/trans. Maintenance records are also a must-see. If the car belonged to a long-distance commuter they should be tracking maintenance and gas-mileage religiously. But ultimately it doesn't matter, hard driving on the highway can be rough on a car, braking at high speeds, hard accelerations to pass, etc., uneven roads at 70MPH can inflict a great deal of wear, more so than 25MPH in stop-and-go traffic. In favor of highway miles however, you want to consider the time spent by an engine running but not moving. A car like a Ford Crown Vic can track idle hours. Idle hours won't be reflected by the odometer. To me at least, I'm less concerned with HOW the miles got on a car, than I am with the overall condition of the car, records, and provenance.

Just go by the overall condition of the car and have it inspected by a trusted mechanic. If the car has 50,000 miles in one year you know most of that was highway.

If the owner is or was a Uber driver pass!

Buying another Sprinter Mark?