Even though gas prices are high, many of us will still pile into our cars as the most economical means for visiting family and friends.

See also: Does idling your car waste fuel?

Here are some ways to make sure you keep your trip expenses (gas, meals etc.) in check.

• Tune it up: Simple maintenance—keeping tires properly inflated, using the recommended grade of gasoline, and replacing clogged air filters—can easily increase fuel efficiency by 10 percent or more, according to some fuel-economy sites like www.fueleconomy.gov. A tune-up will likely save you even more in gas: Just fixing a faulty oxygen sensor, for example, could improve your mileage by as much as 40 percent! Now you could buy gallons of eggnog with that kind of savings.    
  

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• Slow it down: According to www.fueleconomy.gov, for every five miles per hour you drive over the rate of 60 miles per hour, you're essentially paying almost 25 cents more for each gallon of gas. That's how dramatically gas mileage decreases beyond standard speed limits of 55-60 mph. That's also not factoring in the cost of the speeding tickets you're more likely to get at high speeds. To the same end, aggressive driving—rapid acceleration, fast cornering, and sudden breaking—can lower your gas mileage by as much as a third. To help break yourself of those bad driving habits, try keeping a cup of cold water—filled to the brim—in the cup holder on your dashboard. Your goal is to drive so smoothly that you never spill a drop. (If that doesn't work, pop a Perry Como Christmas album in the CD player. That always calms me down.)
  

Next: Park your car and rent one instead. »