A well-tuned engine runs at peak efficiency, giving you the best gas mileage and performance possible. You should have a complete tune-up at least as often as specified in your owner’s manual—more frequently if you do a lot of stop-and-go driving or heavy towing.
Think of the tune-up as part of regular preventive maintenance, not as a cure-all for whatever ails your engine. If you experience a specific problem between tune-ups, tell your technician. Describe the symptoms and the circumstances in which they occur in as much detail as possible. That way, you can head off unnecessary expense and won’t drive off disappointed.