The Carlisle Mosquito Online

Friday, October 15, 2010


The drive behind higher MPG

No matter what car we drive, we can easily control our gasoline use to help the environment as well as our pocketbook. U.S. oil production peaked in 1970, and by 2005 imports were twice the domestic production. Shortages and higher prices seem inevitable, so it’s crucial that we control our consumption of this limited resource that also contributes to climate change.

The graph below, from, shows that typical fuel economy drops almost 10% for every five mph we drive over 60 mph, due to aerodynamic drag. This website also lists the most fuel-efficient car models within each class.

Tire pressure

Correct tire pressure is listed in a car’s owner’s manual. Tires that are under-inflated by ten pounds per square inch (psi) can reduce gas mileage by 5%. Low pressure is not always obvious by looking at the tire. Check the tire pressure when the tires are cold (if they are hot, allow for an extra four lbs of pressure), and avoid pencil-type gauges, which tend to be inaccurate. Some people use an extra three to four lbs of pressure to increase mileage and to decrease tire wear (without significantly affecting performance), and to allow for air leakage. Pressure will be reduced by about one psi for each ten degree drop in outside temperature, so it’s important to check tire pressure once a month or so as the seasons change.

Other gas-saving tips:

the cars we drive

It may be counter-intuitive, but replacing a low-mileage car with a moderate-mileage car has a much bigger benefit than replacing a moderate-mileage car with a high-mileage car. For example, a gas guzzling ten mpg car consumes six gallons to drive 60 miles, while a 20 mpg car uses three gallons and a high-efficiency 60 mpg car uses only one gallon. Replacing a ten mpg car with a 20 mpg car saves three gallons for every 60 miles driven, whereas replacing a 20 mpg car with a 60 mpg car saves 33% less, or two gallons. It’s therefore most important to get rid of the gas guzzlers.

Practice anti-idling

The Carlisle Selectmen recently approved a program to promote awareness of the state’s anti-idling law that bans unnecessary car and bus idling, especially at locations such as the school and post office. The purpose of this law is to reduce air pollution while saving gasoline. (See the Mosquito Green Corner of 9/11/09).

Driving behavior

Other tips to save money on gas, from, include: driving smoothly, reducing unnecessary drag from car-top carriers (these can reduce economy by almost 20% at 65 mph), not using premium fuel unless your car owner’s manual requires it, minimizing running on a cold engine by combining trips as much as possible.

Support environmentally responsible gas stations

Oil companies embrace “green washing” as many other businesses do to boost sales and public opinion of their product. Some gas station companies make more of an effort to lessen their impact on the environment than others. We can support the best ones with our business. Their ranking, from best to worst in environmental and social responsibility (according to The Better World Handbook by Ellis Jones, et al., Sunoco, BP, Citgo, Shell, Texaco/Chevron, Conoco/Phillips and Exxon/Mobil. The better companies recognize climate change, support the Kyoto Protocol to reduce greenhouse gas emissions, invest in alternative energy research, belong to the Business Environmental Leadership Council (BELC) and signed the Coalition for Environmentally Responsible Economies (CERES) principles. Companies low on the list deny that global warming exists, and seek to drill in the Arctic National Wildlife Refuge (ANWR).

When filling up, look for a station that has a [thick] vapor recirculation pump hose so the gases in your tank are not forced into the outside air. Also, do not top off the tank, which can clog the nozzle and cause spillage. To find a local low-priced gas station, current gasoline prices are searchable by town at ∆

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