Preparing Your Vehicle

It's no secret that the price of energy has been rising recently. Anyone who has put gas in a car lately has run into that fact. If you'd like to save money on gas, this article will offer tips on how to drive economically.

Tires: A Vital Consideration

Proper tire inflation is critical to fuel economy, and to safety. Underinflated tires cause vehicle drag and increase fuel consumption. They also compromise handling ability in turns and in emergency maneuvers. They increase stopping distances and decrease control during braking. Under-inflation puts undue stress on tire sidewalls and also causes rolling tires to build and retain heat rapidly. Stress and heat are prime contributors to tire failure, including blowouts at high speed. Underinflated tires also wear down more quickly.

Properly inflated tires are harder and roll more easily. That helps fuel economy and improves tire life. It allows the treads to grip well in all conditions, including rain and snow. And properly inflated tires are able to work with your vehicle's suspension to provide maximum handling, steering, and braking ability.

An estimated four out of ten vehicles on the road have at least one underinflated tire. Pressure that's 3 pounds per square inch (psi) below the recommended reading may reduce gas mileage by 1.5 percent. Some experts suggest even greater decreases. The Environmental Protection Agency (EPA) warns that running tires at 20 psi or lower can easily cost you a full mile per gallon.

Proper tire inflation: Tires can naturally lose up to 1 psi every 30 days, and they will lose pressure more quickly in cold weather. Because cooler air is more dense, pressure drops by about 1 psi for every 10 degrees. A tire inflated to 30 psi at 70 degrees, for example, could drop as low as 26 psi at the freezing point.

The recommended tire pressure is displayed in your vehicle, typically on a sticker inside the glove box door or on one of the doorposts. It's also in your owner's manual. Many vehicles are available with a choice of tire sizes, and each size may have its own recommended inflation pressure.

Match the tire size as listed on the tire sidewall with that on the sticker or in the owner's manual. Note that the inflation number listed on the tire sidewall itself shows the maximum inflation, not the optimal pressure as determined by the tire maker and the manufacturer of your vehicle.

Checking tire inflation: Check inflation when the tires are cool. That means they have been driven less than a mile or so. Air expands inside a warm tire, which will give you a false reading.

Tire pressure should be checked at least every 30 days. A tire gauge is the old standby. But federal regulations require that by 2008 all new cars, sports utility vehicles, minivans, and pickup trucks be equipped with an underinflation warning system. Sensors will monitor tire pressure, and if it falls 25 percent below the recommended inflation, a yellow warning light on the dashboard will illuminate.

The system will save an estimated 120 lives and prevent 8,400 injuries annually, according to the National Highway Traffic Safety Administration. NHTSA estimates it will also save drivers up to $35 annually because of longer tread life and decreased fuel costs. Select 2004 and 2005 models already have such a system. For the 2006 model year, 20 percent of new vehicles must have the system, with 70 percent for 2007, and 100 percent for 2008.

Fuel economy varies with tire type: Those all-terrain or off-road tires with their knobby tread look rough and ready and are designed to get you through rocks and mud. They are not designed to promote high gas mileage.

All-season tires produce less friction and therefore roll more freely to the benefit of fuel economy. They're generally lighter than all-terrain or off-road tires, and less weight means better fuel economy. They also ride more quietly, handle better, and wear longer.

Don't Carry More Than You Need

Keep the car as light as reasonably possible. For each 100 pounds of extra weight, gas mileage is reduced by as much as 4 percent. Limit the everyday items in your trunk or cargo area to the bare necessities, which should include some emergency items, such as a small jug of water, a flashlight, and a few tools.

Don't haul around what you won't be using. Leave the golf clubs at home until you head for the links. Not only does extra bulk add fuel-gulping weight, but it can also upset your vehicle's normal weight distribution. That will impair handling and can even rob a front-wheel-drive car of valuable traction. If you must carry heavy items, try to put only a few of them inside the car at a time.

Remove That Rack

Wind drag increases fuel consumption. Get rid of anything that disturbs the smooth flow of air over your vehicle's surface. Most roof racks have removable cross members, and some racks can be removed altogether; take off your car's rack if it isn't in use. When you do need to carry something on the roof, keep it light and small -- both for fuel-saving aero-dynamics and to avoid the risk of a top-heavy weight imbalance.

That grille bar and those running boards may make your SUV look rugged, but they also add weight and drag. And that bolt-on trunk-lid spoiler that makes you feel fast and furious? It's designed to harness the wind and press your car to the pavement at high speeds. The result is better grip on the road, but this "downforce" is actually artificial weight that hurts fuel economy. Worse, unless you are a racing technician versed in aerodynamics, chances are excellent that your spoiler isn't doing anything more than adding wind drag and weight. That's costing you at the pump, too.

Retain That Tailgate

Some pickup-truck drivers take it as an article of faith that they're saving fuel by driving with the tailgate down, or removed, or replaced by a mesh fabric or metal gate. False.

Aerodynamic studies show a pickup truck is most fuel efficient with its tailgate up. It seems the upright tailgate causes air flowing over the roof of the cab to collect as a stagnant "dome" in the cargo bed. As speed builds, this dome, which tapers in a teardrop shape near the tailgate, acts as an aerodynamic ramp that forces airflow over the tailgate, to the benefit of fuel efficiency.

Disrupt this flow by dropping or removing the tailgate, and air coming over the cab is left to swirl around in the cargo bed, degrading the truck's aerodynamics and hurting fuel economy.

Keeping your vehicle in good shape can help with its fuel efficiency. In the next section, we'll take a look at steps you can take to maintain your vehicle for fuel economy.