Schedule Regular Maintenance
Cars that start quickly, run smoothly, and are in good mechanical condition get the best gas mileage. Whatever cuts into performance hurts economy. Scheduled maintenance also helps make parts last longer, so you save money two ways: today in economy, tomorrow in reduced repair costs.
A tune-up can boost fuel economy up to 10 percent, says the EPA. On modern fuel-injected cars equipped with computer-controlled powertrain systems, there's actually little to "tune up." Basically, today's tune-up means replacing the spark plugs, although it's also important to perform the kind of preventive maintenance described later in this section.
Follow The Schedule
Your owner's manual will likely list two maintenance schedules: one for "ordinary" driving; the other for "severe" or "heavy-duty" use. Each has its own maintenance program and lists the systems to be checked and the work to be done based on both mileage and time elapsed between servicing.
Even if you don't tow a trailer or drive in dusty conditions, your "ordinary" use can fall into the heavy-duty category if you live in a region subject to very hot or very cold temperatures. Even driving your vehicle on frequent short trips counts as heavy-duty use.
When in doubt, err toward the stricter maintenance schedule. It'll pay off in fuel savings weekly, and in long-term reliability.
Emissions and Fuel Economy
Bringing your car's emissions down to within specifications can improve gas mileage as much as 15 percent. And your engine will last longer, too. The oxygen sensor is a key part of your emissions system, and some estimates suggest that a faulty oxygen sensor can reduce fuel economy by as much as 40 percent.
Under federal law, most emissions controls are covered by the factory warranty for 5 years or 50,000 miles. And some emissions-related repairs may be covered at no cost to you.
Look, Listen, and Sniff
Be alert for anything odd. Open the hood and look for loose wires or hoses. Check fluid levels regularly, as described later in this section. Be aware of any sudden drop in fuel economy or a curious odor. Monitor the coolant-temperature gauge, if your vehicle has one. As we'll see, running too cold costs fuel. Take note of any pinging or odd noises, hard starting, or significant loss of power.
In the next section, we'll discuss some simple do-it-yourself gas-saving maintenance that can increase your vehicle's fuel efficiency.