Idling gets zero miles per gallon and vehicles with larger engines typically waste more gas when they idle than those with smaller engines.

As a rule of thumb, the U.S. Department of Energy reports that you can assume that each 5 mph you drive over 60 mph is like paying an additional 20 cents per gallon for gas.

On the highway, using cruise control helps drivers maintain a constant speed and generally saves gas.

Protect Vehicles from Fuel Theft. With sky-high gas prices, police departments around the country are finding more instances of gas being siphoned from vehicles.

One company in Shreveport, LA, added locking gas caps to its fleet of vehicles after spotting someone siphoning fuel from trucks in its parking lot. A not-for-profit food bank in San Jose, CA, was recently the victim of thieves siphoning about 200 gallons from delivery trucks. And even worse, a Rock Hill, SC, day-care center found thieves stole fuel from a bus by cutting the gas line.

Especially vulnerable are businesses with fleets of vehicles that are parked in unlocked, unwatched areas at night.

Plan Ahead to Cut Back. Cluster sales calls, deliveries, appointments and errands to eliminate trips and cut cross-town driving. Try to avoid peak travel times and road construction so you spend less time in traffic.

Your business could, for example, make deliveries only in certain areas on certain days. Making several short trips can consume more than twice as much fuel as one multi-purpose trip covering the same distance when the engine is warm and efficient.

Speaking of deliveries, if your company offers them for free, consider eliminating the practice or reducing the free area and charging for deliveries outside that radius.

Consider Buying More Efficient Vehicles. The Energy Department reports that the difference between a car that gets 20 MPG and one that gets 30 MPG amounts to $878 per year (assuming 15,000 miles of driving annually and a fuel cost of $3.51). That's an extra $4,388 in fuel costs over five years. Click here to access the federal government's Web site, which allows you to find and compare energy-efficient passenger vehicles.

Keep Vehicles in Tip-Top Shape. Simple and regular maintenance can help reduce the cost of operating your company's vehicles, as well as improve safety. For example, keep engines tuned, replace air filters regularly, keep tires properly inflated and use the recommended grade of motor oil.

According to the Energy Department, fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve your mileage by as much as 40 percent.

Remove Excess Weight. Don't keep unnecessary, heavy items in vehicles. The Energy Department reports that an extra 100 pounds in a vehicle could reduce its MPG by up to 2 percent. Removing it could save 4 to 7 cents per gallon, depending on the vehicle weight.

Of course, gasoline isn't the only expense involved in operating a single car or a fleet. You must also take into account expenses such as financing, taxes, insurance, depreciation and trade-in values. But with today's record-high gas prices, it pays to improve the fuel efficiency of your vehicles.