As of 2015, the traditional auto tuneup is no longer necessary, according to Cars.com. With electronic ignitions and onboard computers, automobiles automatically compensate for parts that used to require regular replacement. The only two parts from the traditional tuneup that still require changing are the air filter and spark plugs.
The service manual for most modern automobiles recommends changing the air filter every 30,000 miles. Changing the air filter does not improve the gas mileage of the vehicle. However, it does improve acceleration. If the vehicle operates under heavy working conditions, such as towing or in dusty environments, the filter sometimes requires more frequent filter changes.
Maintenance schedules also recommend changing spark plugs every 100,000 miles. The vehicle's onboard computer system automatically adjusts for any wearing away of the electrode due to use and keeps the vehicle operating efficiently.
While vehicles no longer require tuneups, they do require regular maintenance. Manufacturers include the maintenance schedule with the owner's manual. Providing regularly scheduled maintenance increases the fuel economy of operating a vehicle. A single bad oxygen sensor has the potential of reducing economy by 40 percent. During the maintenance phase, the mechanic also inspects the fuel system, vacuum hoses and other parts that affect the fuel economy.