Surefire ways to stay one step ahead in the gas-savings game
August 2008
It seems as though ways to save money on gasoline are all people talk about these days—especially on the Internet.
Public transportation, carpooling, and turning off the air conditioner and opening windows (unless you are on the freeway because open windows hinder aerodynamics) are some of the tips that appeared on practically every list of ways to save on gas. But for those who want to set their own driving schedule, there are a few more recommendations that can be stored in your dollar-saving database and some tips that are deemed as fictitious as cheap gas itself.
An e-mail being sent around to who-knows-how-many people offers some gas-saving ideas that sound inventive, but feelings are mixed among experts as to their validity.
The e-mail claims to have been written by someone who has worked in petroleum for 31 years and says “here at the Kinder Morgan Pipeline where I work in San Jose, we deliver about 4 million gallons in a 24-hour period thru the pipeline.”
There is no name attached, and a Kinder Morgan representative said that the company does not know from where the e-mail originated.
In any case, the message’s suggestions are as follows, followed by a quick reaction from experts in the field:
Only fill up your car or truck in the early morning when the ground temperature is still cold. Remember that all service stations have their storage tanks buried below ground. The colder the ground the more dense the gasoline; when it gets warmer gasoline expands, so buying in the afternoon or in the evening….your gallon is not exactly a gallon. In the petroleum business, the specific gravity and the temperature of the gasoline, diesel and jet fuel, ethanol and other petroleum products plays an important role. A 1-degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.
“I think it could be true because of the physics of heat and expansion,” said Pasadena City College automotive lab technician Wendy Lucko. “But the gas pump meters meter so well now. They are not like the old pumps where it was just based on how much time it would pump. Now it’s just pumping volume so if it saves you a fraction of a gallon I don’t think it’s even worth it to wait when you have a time constraint for work and everything else.”
“The Bureau of Weights and Measures did a study about gas expanding and you’d have to check with them, but I don’t believe it showed any wholesale reduction,” said Automobile Club of Southern California spokesperson Marie Montgomery.
“The tanks are stored underground and most things stay at a constant temperature,” said PCC chemistry professor Claudia Barner. “It sounds like an urban legend and I can’t imagine it making a big difference.”
When you’re filling up do not squeeze the trigger of the nozzle to a fast mode. If you look you will see that the trigger has three stages: low, middle, and high. In slow mode you should be pumping on low speed, thereby minimizing the vapors that are created while you are pumping. All hoses at the pump have a vapor return. If you are pumping on the fast rate, some of the liquid that goes to your tank becomes vapor. Those vapors are being sucked up and back into the underground storage tank so you’re getting less for your money.
“If you fill up slower it is probably better for the environment than for your gas tanks because you are not releasing the hydrocarbons into the atmosphere,” said Lucko. “In California all the gas pumps are sealed. In other places they don’t and have a straight nozzle and you can see the hydrocarbons coming out of the tank as you are filling it.”
“None of that makes any difference,” said Montgomery. “Those pumps are regulated by the Bureau of Weights and Measures and they are supposed to test throughout the state and make sure that the pumps are operating and that the price you pay and the amount you are getting is all consistent.”
Fill up when your gas tank is half full or half empty. The more gas you have in your tank, the less air is occupying its empty space. Gasoline evaporates faster than you can imagine. Gasoline storage tanks have an internal floating roof. This roof serves as zero clearance between the gas and the atmosphere, so it minimizes the evaporation. Unlike service stations, here where I work, every truck that we load is temperature compensated so that every gallon is actually the exact amount.
“That’s not necessarily true,” said Lucko. “I think mostly it is just the weight. Your fuel pump is in your tank and needs fuel to stay cool so you don’t want to run low all the time because you’ll burn out your fuel pump. But if you have at least half a tank in it, the pump is submerged so it keeps cool and you are carrying less weight versus having a full tank all the time. Gas is roughly eight pounds to a gallon so it’s like carrying another human being when you have a full tank.”
In this case, “evaporation is not a factor that I know of,” said Montgomery. But she feels it is “not a bad idea. You don’t really want to run your gas tank down to ‘E’ because there is sediment at the bottom of the tank and it gets in the fuel line and can cause problems and reduce your fuel economy. So it is a good idea, maybe at a quarter or half a tank, to fill it up again.”
If there is a gasoline truck pumping into the storage tanks when you stop to buy gas, do not fill up—most likely the gasoline is being stirred up as the gas is being delivered, and you might pick up some of the dirt that normally settles on the bottom.
“That makes sense to me because no matter how good the station is—the underground tanks are getting a lot better now—but there is always sediment on the bottom of those tankers anyway,” said Lucko. “That filter is what is going to take the grunge off it. Make sure you change the fuel filter.”
“We’ve never been able to ascertain that makes a difference whatsoever,” said Montgomery.
In addition to questionable e-mails, sketchy gas-conserving driving techniques such as hypermiling, in which a driver turns off the engine at stop lights, are gaining exposure on CNN and other media outlets.
The Pasadena Police Department has had no reports of dangerous driving activity as a result of rising gas prices, but “that doesn’t mean it can’t change,” said Pasadena Police Department public information officer Janet Pope-Givens. “We would encourage people to practice safe driving habits.”
Lucko finds the hypermiling techniques laughable.
“It’s so dangerous how most people can drive with the car on,” said Lucko. “Can you imagine shutting it off? I think they put the car in neutral to start it and then coast around corners without stepping on the brakes, but you create so much speed with the centrifugal force around the turn. For what it would save you I don’t think it’s worth it. There are going to be people that try it and get in accidents and try to blame it on the news.”
While some dangerous driving techniques are touted as fuel savers, others will deplete fuel significantly.
“Something that can make a difference of 20 to 40 percent in the amount of fuel you consume is how you drive,” said Montgomery. “The more smooth and even you can make your driving style, the better your fuel economy will be. If you are one of these speed demons who goes 80 miles an hour, or if when the light goes from red to green you slam on your gas, all of that wastes a ton of gas.”
Montgomery said the optimum speed for fuel efficiency is 55 to 65 miles an hour and she recommends using cruise control on an empty freeway or coasting to stops in a residential area when no one is behind you.
Lucko and Montgomery agree that removing excess weight and car maintenance like tune-ups, clean fuel filters and checking tire pressure at least once a month to make sure they are properly inflated are the main things that will help conserve gas.
“Pasadena in general is a pretty walker-friendly city, depending on what part you live in,” said Montgomery. “There’s maybe more opportunities than in other communities to use alternate routes of transportation. You have got the gold line and your store needs close by. I think people are sort of waking up to that awareness of not driving to the grocery store but maybe walking, getting some exercise and taking groceries home.”
