Running on empty: Low gas in the tank can be costly

Most motorists today are pained at the thought of filling up with gasoline as prices hover around $4.00, but for those who put off the fuel stop until the last possibly moment, the costs could be even higher.

Waiting until your gas tank is almost empty before a fill up can be pricey, could be dangerous and downright inconvenient. “While the cases are rare, there is real potential of a costly mechanical problem,” says Consumer Reports Auto Test Center shop supervisor and certified mechanic John Ibbotson.

The gasoline acts like a coolant for the electric fuel-pump motor, so when you run very low, this allows the pump to suck in air, which creates heat and can cause the fuel pump to wear prematurely and potentially fail. The repair could end up costing a couple hundred dollars to fix—much more than the $4.00/gallon fill up.

Also, if there is dirt in the fuel tank, it could lead to blocking the fuel filter; again, another expensive repair.

Another effect of driving on a low tank is the risk of getting stranded or even in an accident when the car suddenly stops running--you could be in the middle of a busy highway or on a deserted road.

Luckily, these scary scenarios are preventable. Here are some tips to keep in mind to avoid running out of gas.

• Keep your gas tank no less than ¼ full.
  
• Fill up before heading out on a long trip or to work as you could get stuck in traffic and have a longer ride than intended.
  
• Don’t rely on your car to tell you how many miles are left, as those range numbers can be deceiving and run down quickly, depending on how you drive.
  
• We all want to save money at the pump, but instead of driving miles away to the gas station, use online tools or even smart phone apps to find the cheapest gas near your house.

So far, AAA hasn’t seen any measurable increase in roadside assistance calls for running out of gas—it’s still about 2 percent of the 30 million calls they receive each year. Let’s hope it stays that way, for cars stuck on the roadside are dangerous and can lead to traffic congestion, which in turn can reduce the fuel economy for hundreds of passersby.

For more on saving gas and for tips on how to maximize the fuel in your vehicle, see our guide to fuel economy.

—Liza Barth