A Green Idea: No Left Turns

By Peter DeMarco, Globe Correspondent

Tuesday is Earth Day, but this year I’m not thinking green; I’m thinking brown, as in Big Brown, United Parcel Service.

Why UPS? Because I just found out a fairly crazy fact about UPS drivers: They make a conscious effort not to make left-hand turns.

Company leaders figured out that sitting in traffic, waiting to make a left, burns way too much fuel. So they zapped as many left turns as they could from 100,000 truck routes a day.

Instead, drivers are handed computer-generated delivery routes that have them going in efficiently calculated loops, calling for left turns only when necessary.

‘‘You start on the right-hand side of the street and you stay on the right-hand side of the street almost all of the day,’’ said Dan McMackin, a former UPS driver who is now a company spokesman. ‘‘The only left turn you make is to come home.’’

According to the company, this simple technique saves an eye- popping amount of gasoline. ‘‘In the last year alone,’’ a UPS release stated, ‘‘this system has shaved nearly 30 million miles off UPS’s delivery routes, saved 3 million gallons of gas, and reduced emissions by 32,000 metric tons of CO2 — the equivalent of removing 5,300 passenger cars off the road for an entire year.’’

I doubt any of us can make it through the day without left-hand turns. (Even UPS drivers can’t avoid making them in a city as congested as Boston, says Jimmy, my local delivery guy.) But I like what UPS does because it proves you don’t have to own a hybrid to save gasoline; you just
need to tweak the way you drive. And you might be shocked at how much gas you can potentially save.

Still skeptical? Let me direct you to fueleconomy.gov, a terrific government website that breaks down in dollars and cents just how much fuel you waste when you drive over 60 miles per hour, have low air pressure in your tires, or fail to replace a clogged air filter.

How much gas could you be wasting on just these three items? Let’s add it up.

Most engines don’t run efficiently past 60 miles per hour. For every 5 miles per hour you drive over 60, you’re probably wasting 20 cents’ worth
of gasoline per gallon, according to the US Environmental Protection Agency and the US Department of Energy, which cosponsor fueleconomy.gov. (The 20 cents is based on a cost of $3.23 a gallon.)

The amount of waste is smaller for economy cars and higher on big
SUVs. But on average, if you drive 70 on the highway, you’re essentially
wasting 40 cents of gas per gallon.

If your tire pressure is too low, you’re burning an extra 10 cents of gas per gallon.

Replacing a clogged air filter can improve your car’s gas mileage by
as much as 10 percent, the EPA states. A dirty air filter, which keeps
impurities out of your engine, translates to a waste of about 32 cents of
gasoline per gallon, based on current prices.

All told, that’s 82 cents of gasoline you’re wasting per gallon. Worried about paying more than $4 a gallon for fuel this summer? Guess what: If you’re wasting this much gas, you already are.

David Greene, fueleconomy.gov’s senior researcher, said, however,
that most drivers aren’t wasting that much fuel. Most people do replace
their air filters, he said. Most people spend only a half or third of their
driving time on a highway, and even then, they’re not always going faster
than 60, he said.

Still, your driving attitude absolutely can affect your car’s mileage. If you’re serious about saving gas, then no more speeding, no more tailgating and slamming on the brakes, no more leaving your weighty golf clubs in the back seat all year long, no more warming up your car for 10 minutes in the winter, no more gunning your engine at a green light, no
more skipping your regular tune-up, and no more — dare I say it — beating everyone else on the road so you get there first.

Indeed, perhaps the most important gas-saving tip, aside from
keeping your car in good shape, is simply to stop driving so aggressively,
Greene says.

‘‘That’s the thing you have the most control over, and has the biggest impact.’’

Aggressive driving (speeding, rapid acceleration, braking) can lower gas mileage by 33 percent at highway speeds and by 5 percent around town. If you split your driving time between the two, you’re wasting about 45 cents per gallon, all because you’re in a rush.

Of course, it’s a tall order to ask Boston drivers to drive less aggressively. But at least one group of drivers I found proves it can be done.

Toyota’s uber-efficient Prius hybrid gets great mileage not only because it uses electricity, but because Prius owners make a game out of
saving gas.

Each car has what’s called an ‘‘instantaneous fuel economy gauge’’
that shows your miles per gallon for each moment you’re driving. If you
floor it at a yellow light, your gauge will drop to 10 or 12 miles to the gallon because your engine’s working too hard, says Toyota spokesman Bill Kwong. If you’re coasting down a big hill, your gauge will soar to something like 90 miles to the gallon because you’re letting gravity do the work.

‘‘It’s no different than the old days [the 1970s] when people used
vacuum gauges to monitor their engine efficiency,’’ Kwong said. To maintain a high trip miles per gallon, drivers learn to ease into stops, coast
downhill, maintain steady speeds on highways, and avoid idling.

Kwong, who owns a Prius, said he’s learned to increase his average
trip miles per gallon by 5 or 6 miles by driving ‘‘conservatively.’’ Were
you to start driving like Kwong, the same gains would apply for your nonhybrid as well.

You can find a horde of fuel saving tips at fueleconomy.gov, on
AAA’s website, or at Edmunds.com.