There are a few common signs your vehicle is in need of a tune-up. One is that it's simply riding rougher than usual, or not as smooth and noiseless to drive. Another is that your gas mileage appears to getting worse. This is where the 30/60/90 rule comes in. In an effort to avoid costly repairs, United Transmission recommends regularly scheduled maintenance, or a tune-up, every 30,000 miles (otherwise known as 30/60/90K). Typically the first step in a tune-up is to inspect the vehicle's major systems for signs of trouble or impending trouble. Three of the most important reasons to have regular tune-ups include: air filter inspection, fluid level check, and spark plug assessment. Catching issues with these components will extend the life of your car and save you considerable time and money!