Questions and Answers

Which Is Better: City Or Highway Miles? Q. Hello, I always hear about how highway driving is a lot better than city driving for a car, but I was just wondering, because I'm constantly on the freeway or the tollway, if consistent high speed driving on a car is bad for it, or what the ideal speed is to run a car at to minimize negative effects on the car.

I have a 1995 Toyota Corolla, manual transmission, with high miles, over 130,000, if that makes any difference at all.

Thanks a lot!
Annie

A. I was once asked why cars can go 100 to 130 mph when it is nowhere near legal to do so. And the reason is a large part of the answer to your question.

An engine is designed to cruise at speeds of 50 to 70 mph. This speed is in the mid-range of the engines capabilities. If the engine was given a maximum speed of 50 to 70 mph, and you cruised at that speed, the engine would be working extremely hard and it's life would be significantly shortened.

By cruising in the mid-range, the engine working a lot easier. It's like a person can walk a lot further then he can run.

I don't believe there is an "ideal" speed. There are too many variables involved, road conditions, weather and driving habits.

Highway driving is better on engines than city driving. On the highway you are going at a steady speed, oil pressure is higher so internal engine parts are better protected and engine temperature is stable. Transmissions last longer since they don't shift as often. Transmissions only wear when they shift. As a side effect, brakes last longer simply because you go so many miles between brake applications.

On the other hand, city driving is tough on cars. You are constantly accelerating and decelerating. The transmission is constantly shifting up and down which accelerates wear and the engine idles lower reducing oil pressure and causing more wear on internal engine parts. You use your brakes more often so they will wear out quicker as well.

I guess it would be like a person standing still, then running full speed only to slow down and stop a short time later, and repeating this all day.

In short, engines like to cruise in their mid-range and will do that all day long.