A drop of gas info could save gallons

By Daniel Squadron

This holiday season, millions of Americans will take to the road — and spend literally billions of dollars on fuel. We’ll be reminded once again that buying a car is not just a one-time expenditure. The cost adds up: a few more dollars every time you fill up at the pump.

Of course, it’s not just economics. Between global warming and the other negative effects of burning fuel, a growing number of consumers worry about the environmental impact as well.

Right now, consumers use the standard miles-per-gallon calculation to compare fuel efficiency. And it seems pretty straightforward: it’s obvious that a Hummer (16 M.P.G.) will burn a lot more gas over time than a Prius (46 M.P.G.).

But when consumers try to compare the relative efficiency, as they usually do, the miles-per-gallon measurement falls short. For example, take this pop quiz: two families want to save money on gas. Family A upgrades from a 10 M.P.G. to a 15 M.P.G. light truck. Family B upgrades from a 25 M.P.G. to a 45 M.P.G. sedan. Over the next 1,000 miles, who has saved more gas?

If you chose Family B, you’d be like most people — and you’d be wrong. Over 1,000 miles, switching from 10 to 15 M.P.G. will save you 33 gallons. Switching from 25 to 45 M.P.G. will only save you 18 gallons. (That’s because miles per gallon is calculating the inverse of the question — the M.P.G. rating keeps gallons constant while measuring miles traveled, while a true efficiency rating keeps miles constant while measuring gallons used.)

Don’t worry, studies show that most consumers get miles per gallon comparisons wrong, as I did when I first took the quiz.

At the dealership, getting this question wrong is bad — for your wallet and the environment.

The most important question for consumers is on efficiency: given the numbers of miles I drive (the daily commute, trips to soccer practice, the annual pilgrimage to Florida) and the type of car I need (most people are not choosing between a Hummer and a Prius), how many gallons of gas will I need to buy?

To answer this question correctly, instead of miles per gallon, consumers need to know their gallons per mile.

Gallons per mile (G.P.M.) measures how much fuel must be burned in order to go a set distance — for example, 1,000 miles. Just multiply that by the price of gas in your neighborhood, and you know exactly how much it will cost you to drive 1,000 miles. Using G.P.M., you can compare how much gas you would have to buy for each car on the lot.

I have introduced a bill that would require auto dealers to affix a gallons-per-mile “fuel impact statement” on all new vehicles sold in New York State. Consumers will be able to see how many gallons of gas the car will use to go 1,000 miles, and they can make educated choices about which cars will truly save the most gas, and the most money, over time.

For one family, better information about their cost of gas can save hundreds of dollars in a year. When you multiply that by 19.5 million New Yorkers, the fuel savings is in the millions — and that’s a big step in the fight against climate change.

Knowing how much fuel your new car will actually use: not a bad achievement for a sticker in a car lot.

Daniel Squadron represents the 25th State Senate District, which covers most of Lower Manhattan and Downtown Brooklyn.