What's Better for a Car: Highway or City Miles?

It's a common occurrence that when you see a car with very high mileage but is in otherwise good shape, someone will say, "those 160,000 miles must be mostly highway miles." 

Is this common perception — that highway miles are somehow easier on a car than "city" miles — actually true? And if so, why?

Engineered for Cruising Speed

Most engines in automobiles are designed for a cruising speed of 50 to 70 mph or so. This speed is in the mid-range of the engine's capabilities. Many consumer cars off the factory floor can achieve speeds of 100 to 130 mph, a range that falls at the very top end of their engineered capabilities. If you regularly cruised at 100 mph, your engine would have to work much harder every day, causing increased wear. By cruising in the mid-range, the engine is working in its comfort zone.

Steadiness, Not Speed

It's is hard to identify an ideal speed for a given car. Some vehicles will cruise very nicely at 80 mph for hours on end, while another will struggle mightily. Some cars seem to resent cruising at 50 mph, while for others this is the ideal speed. Rather than speed itself, though, it is really the steadiness of the speed that has more impact on engine wear. When an optimal speed is maintained steadily, the oil pressure remains higher so internal engine parts are better protected and engine temperatures remain stable. Transmissions also last longer, since they don't shift as often. Frequent shifting places the most wear on gears and transmission linkage. Additionally, brake pads and brake discs last longer simply because you go so many miles between brake applications.​

All of these things together make for an ideal situation for a vehicle. If you've ever heard a driving enthusiast refer to the feeling of their favorite car "at speed," they are talking about a smooth, fast drive, one that leaves the systems of the car performing perfectly together like a well-rehearsed orchestra.

The Problems With City Driving

City driving is the antithesis of the perfect conditions offered by highway driving. You are constantly accelerating and decelerating, the transmission is constantly shifting up and down, which accelerates wear, and the engine frequently idles at low RPMs, reducing oil pressure and causing more wear on internal engine parts. You use your brakes more often so they will wear out quicker.

The wear of city driving can be minimized by more frequent maintenance cycles. A car with a recommended oil-change interval of 7,500 miles might really require changes at 5,000 or even 3,000 miles if it sees nothing but stop-and-go use in heavy traffic. Brake pads and tires that might last 70,000 miles in highway driving should be inspected every 25,000 miles or so. 

This is one piece of conventional auto wisdom that is 100 percent, absolutely true: a car that sees steady use at highway cruising speeds will last longer and require less maintenance than one that faces the grueling routine of city driving for its whole life. When shopping for a used car, this is an important question to ask, and one that might determine how much you offer for the vehicle: "highway car or city car"?