Published: May 25, 2008 12:17 am      

Questioning consumption

Answers to common questions about how vehicles use gasoline.

Q. Does proper maintenance really impact fuel economy?

A. Norm Truax, co-owner and operator of Logan Tire, says yes. Properly inflated tires, clean air filters, good breaks and a tuned engine can improve a vehicle’s overall fuel efficiency by up to 10 percent.

Q. Are higher octane fuels better for cars?

A. Not necessarily, say auto manufacturers. Check the car’s manual to see what fuel type is recommended, then stick with that for optimum auto operation.

Q. What’s the best grade of motor oil to buy?

A. Again, go with manufacturer recommendations, says the Indiana Attorney General. Using the wrong grade of motor oil can lower gas mileage by 1 to 2 percent.

Q. Do cars burn more fuel on hotter days?

A. A warm engine operating under normal circumstances actually burns less fuel than a cold one, says Truax. Cold engines will burn more fuel until they heat up. Keeping a car in a heated garage during the winter can help an engine heat faster. However, using the air conditioner on particularly hot days does decrease fuel economy.

Q. How much does weight impact gas mileage?

A. Most auto manufacturers have made considerations for operational weight, says Truax. So a large load of groceries or a set of golf clubs in the trunk won’t affect fuel economy that much. But larger items, like trailers or other heavy loads, will eat into a car’s gas mileage.

Q. Is it better to shut a car off or let it idle?

A. A car that’s shut off burns no fuel, but getting it started again requires a larger initial burst of fuel than is needed during normal running conditions. When stopped at a stoplight, Truax says let the car run. But when stopped at a train crossing or in heavy traffic, shut it off. The Indiana Attorney General also says that larger engines typically waste more gasoline at idle than smaller ones.

Q. How does speed and acceleration affect fuel consumption?

A. According to drivesmarterchallenge.org, a Web site with tips based on auto type, fuel economy for the majority of vehicles goes down rapidly above 60 mph. Speeding up quickly from a stop also requires a larger fuel burst than slower acceleration. Sensible driving can improve fuel economy by 5 to 30 percent.

Q. Does gear usage affect gas usage?

A. The Indiana Attorney General says yes. Engine speed decreases in higher gears, so using the overdrive function can save anywhere from 4 to 40 percent on gas mileage and also reduces engine wear. Using cruise control can also help with fuel economy.

Q. What’s the best time of the week to buy gas in Indiana?

A. According to the Indiana Attorney General, average prices in 2007 were slightly lower on Mondays than on other days.

Q. Will consumers get more gas for the money by pumping it slower?

A. Gas station pumps are inspected regularly to ensure that consumers get what they pay for, says the Indiana Attorney General. So a gallon of gas is the same no matter what speed it’s pumped out at.

Additional sources: indianaconsumer.com, drivesmarterchallenge.org