The term “tune-up” is still used to describe any service designed to make a car run better. This might be replacing spark plugs or correcting ignition problems or fuel usage.
Modern vehicles, though, don’t have many things under the hood that can be adjusted. The engine computer in newer-model cars fixes things automatically, like ignition timing, idle speed, and fuel mixture. There isn’t much left in today’s cars for a mechanic to “tune up.” So, a preventative maintenance visit and a tune-up both describe the same goal—an engine that runs at top efficiency—but the process is different today. No matter what you call it, vehicles of any age need regular preventative maintenance.