Monday, September 25, 2023


Nine easy steps to holding down fuel costs

By Bob Difley

In an article in the Financial Edge newsletter from, Jean Folger points out these nine effective ways to increase your gas mileage by driving more efficiently.

1. Go easy on the pedals
Speeding, braking and rapid acceleration waste gas. Depending on the type of vehicle, these driving habits can negatively affect fuel economy from between 5% and 33%. Based on current prices for gasoline, conservative use of the pedals can lead to gas savings of between 16 cents and $1.03 per gallon.

2. Slow down
Above 60 mph, gas efficiency decreases. According to, for every five miles per hour that exceeds 60 mph, drivers pay an equivalent of about 24 cents more for each gallon of gas. While each vehicle has its own optimal speed, speeding can result in 7% to 23% reduced fuel economy. Driving at slower speeds can save 21 to 71 cents per gallon.

3. Leave extras at home
How many of us drive overloaded motorhomes or pull crammed trailers and fivers? Get rid of the extra bulk and save fuel.

4. Use cruise control (when appropriate)
According to, using cruise control under appropriate conditions (avoid it during especially hilly terrain) can improve fuel economy by up to 14%. That’s a savings of about 43 cents per gallon.

5. Turn off the car
Idling gets zero mph and collectively consumes several billion gallons of fuel per year, according to the U.S. Department of Energy. The California Energy Commission (CEC) advises that vehicles should be turned off if the expected wait will be longer than 10 seconds, since an idling vehicle can burn as much as one gallon of gas each hour. Turning the car off can save about 5 cents per minute.

6. Check tire pressure
According to the U.S. Department of Energy, 1.25 billion gallons of gasoline – approximately 1% of total consumption – are wasted each year on underinflated tires. Tires can lose about 2 pounds per square inch (psi) per month. Each tire that is underinflated by 10 psi reduces fuel economy by about 3.3%. Four tires that are underinflated by 10 psi, then, would reduce a vehicle’s fuel economy by a substantial 10% at an added cost of 31 cents per gallon.

7. Replace spark plugs
The National Institute for Automotive Service Excellence indicates that bad spark plugs can decrease fuel economy by up to 30%, and can cost drivers up to about 94 cents per gallon at today’s prices. If a car’s gas mileage suddenly drops, there’s a good chance it’s because of misfiring spark plugs.

8. Check alignment
Misaligned tires drag instead of roll freely. Improper alignment can reduce fuel efficiency by as much as 10% – about 31 cents per gallon and can wear out more quickly. Tires that are out of balance (symptom: vibration in the steering wheel) can cause uneven tire wear, which can result in lower gas mileage.

9. Fill your tank early in the morning or late at night
Fuel is dispensed by volume. If you fill your tank when it is coolest outside – early in the morning or late at night, and avoid the heat of the day, the fuel will be more dense. As a result, you will get more gas for the same amount of money.

You can find Bob Difley’s RVing e-books on Amazon Kindle.

##RVT828 ##RVDT1402

Russ and Tiña De Maris
Russ and Tiña De Maris
Russ and Tiña went from childhood tent camping to RVing in the 1980s when the ground got too hard. They've been tutored in the ways of RVing (and RV repair) by a series of rigs, from truck campers, to a fifth-wheel, and several travel trailers. In addition to writing scores of articles on RVing topics, they've also taught college classes for folks new to RVing. They authored the book, RV Boondocking Basics.


  1. Auto fuel tank fuel evaporation may have been a problem years ago. Today fuel vapors are scavenged and burned. The tanks are sealed to prevent those vapors from escaping and polluting the atomsphere. There is a check engine code for a bad has cap on every car. Lack of proper tank vacuum triggers this.

    the problem of thanks overflowing after warming up, in my opinion, is not fuel expansion so much as the expansion of the air at the top of the tank. A full tank still has a bit of air.

  2. Back in the dark ages (about 1977, I think) a friend filled her gas tank late at night. The next day in late morning she leaked some gas from her overflow pipe. That may not be the case any more, but it told me not to fill the tank beyond when the nozzle first cuts off.

  3. I was in the US Air Force for my first tour in the military. The aircraft I worked on were fueled at night and by midday the next day vent lines on the planes would spill out 1 or two gallons where we had to hose the area down daily. I used that info for filling my car during the night instead of during the day to save money.

  4. I looked up the last point #9 on Snopes. Below is their posting on the matter:

    Example:   [Collected via e-mail, October 2007]

    I’ve been in petroleum pipeline business for about 31 years, currently working for the Kinder-Morgan Pipeline here in San Jose, CA. We deliver about 4 million gallons in a 24-hour period from the pipe line; one day it’s diesel, the next day it’s jet fuel and gasoline. We have 34 storage tanks here with a total capacity of 16,800,000 gallons. Here are some tricks to help you get your money’s

    1. Fill up your car or truck in the morning when the temperature is still cool. Remember that all service stations have their storage tanks buried below ground; and the colder the ground, the denser the gasoline. When it gets warmer gasoline expands, so if you’re filling up in the afternoon or in the evening, what should be a gallon is not exactly a gallon. In the petroleum business, the specific gravity and temperature of the fuel (gasoline, diesel, jet fuel, ethanol and other petroleum products) are significant. Every truckload that we load is temperature-compensated so that the indicated gallonage is actually the amount pumped. A one-degree rise in temperature is a big deal for businesses, but service stations don’t have temperature compensation at their pumps.
    2. If a tanker truck is filling the station’s tank at the time you want to buy gas, do not fill up; most likely dirt and sludge in the tank is being stirred up when gas is being delivered, and you might be transferring that dirt from the bottom of their tank into your car’s tank.
    3. Fill up when your gas tank is half-full (or half-empty), because the more gas you have in your tank the less air there is and gasoline evaporates rapidly, especially when it’s warm. (Gasoline storage tanks have an internal floating ‘roof’ membrane to act as a barrier between the gas and the atmosphere, thereby minimizing evaporation.)
    4. If you look at the trigger you’ll see that it has three delivery settings: slow, medium and high. When you’re filling up do not squeeze the trigger of the nozzle to the high setting. You should be pumping at the slow setting, thereby minimizing vapors created while you are pumping. Hoses at the pump are corrugated; the corrugations act as a return path for vapor recovery from gas that already has been metered. If you are pumping at the high setting, the agitated gasoline contains more vapor, which is being sucked back into the underground tank so you’re getting less gas for your money. Hope this will help ease your ‘pain at the pump’

    Variations:   In March 2008, the “Tips on pumping gas” e-mail quoted above was combined with the “Don’t buy gas from these folks” e-mail which exhorted motorists to boycott Shell, Chevron, Exxon and Marathon in favor of smaller outfits.
    Origins:   This collection of purported money-saving tips for buying gasoline is another item difficult to classify as strictly true or false. It’s not completely false in that one or more of the tips might actually result in some savings (however modest), but it can’t fairly be classified as true either, as the practical utility of all of these tips is disputed, and the economic gains to be had from following them is highly questionable. Below is a summary of what we’ve gleaned from various sources about the usefulness of these tips:

    Fill up your car or truck in the morning when the temperature is still cool

    The temperature at which gasoline is sold has been the focus of legislative interest of late in several states, the primary issue being that regulators maintain gasoline expands or contracts about 1% for every 15-degree change in the fuel’s temperature. U.S. oil companies and distributors account for temperature when they sell to each other, but most retail outlets in the U.S. (i.e., gas stations that service ordinary motorists) make no such adjustments. The standard used in the oil industry assumes fuel is dispensed at a temperature of 60°F; however, fuel often comes out of service station pumps at considerably higher temperatures (especially in warmer climates), but its volume is still calculated as if it were 60°F, which advocates claim results in customers’ getting a smaller volume of gasoline than they’re paying for. Lawmakers in some states (such as California, Texas, and Missouri) have therefore been considering bills that would force retailers to add temperature-adjusting pumps (Automatic Temperature Compensation, or ATC) in order to bring the gallons-sold tally in line with the 60°F standard.
    (Temperature regulations on gasoline sales are already in effect in some places. Hawaii, for example, requires retail pumps to dispense fuel on the assumption that it is 80°F rather than 60°F. ATC is widely used in Canada, but some critics have noted that Canada’s colder climate means gasoline is often dispensed at temperatures lower than 60°F, resulting in customers’ getting more than they’re paying for — hence the oil industry’s eagerness to embrace ATC in that country while resisting its implementation in the U.S.)
    The whole temperature/volume issue is a subject of lively debate: Some maintain that consumers always get the volume of gas they pay for, regardless of temperature, and the real issue is whether a gallon of warmer, expanded fuel contains as much “energy” as a gallon of cooler fuel. Some say it doesn’t; others maintain that consumers are getting the same “energy content” in a tank of gas either way.
    Moreover, according to some sources the idea that buying gasoline in the morning will guarantee motorists get considerably cooler (and therefore cheaper) fuel is a chimera, as the Los Angeles Times noted:

    Q: Should I buy fuel in the morning or when temperatures are cooler?

    A: No. The delivery temperature is key, because most fuel sits in underground tanks that act like big Thermos bottles. Even if a station receives a load of gas at 5 a.m., if it’s coming straight from the refinery, the fuel will be hot and stay that way.

    Others maintain that regardless of the temperature at which gasoline is delivered, due to the insulative properties of underground storage tanks one can’t be sure that gasoline will always be at its coolest early in the morning.
    In any case, the bottom line is whether it’s really worthwhile for consumers (in the absence of ATC) to take matters into their own hands and attempt to save money by buying gasoline only at a particular time of day. Even if the temperature/volume issue were a real and significant one, one has to consider the amount of savings to be gleaned from such a scheme. Assuming that a motorist typically bought 15 gallons of gasoline per week at $4.00 per gallon, and assuming that by carefully choosing to fill up at a particular time of day said consumer could realize a 1% savings, we calculate the total savings to be gleaned over the course of a year at about $31. Would that reward really be worth the potential inconvenience of adhering to a rigid fill-up schedule week after week?

    If a tanker truck is filling the station’s tank at the time you want to buy gas, do not fill up; most likely dirt and sludge in the tank is being stirred up

    Most sources agree that deliveries from tanker trucks do stir up particles of dirt and sludge in gasoline storage tanks, but that this isn’t really much of an issue for the ordinary motorist. Gas stations are required to have filters that trap dirt and sludge, and modern automobiles also have fuel filters, so a bit of stirred-up dirt doesn’t really pose much potential to adversely affect your car.
    And again, one has to consider the trade-off. On the (probably infrequent) occasions when you arrive at a gas station at the very same time a tanker is filling the station’s tanks, is it really worth the time and expense to leave without filling up and drive off to a different service station just to avoid something that likely isn’t much of a concern in the first place?


    Fill up when your gas tank is half-full (or half-empty), because the more gas you have in your tank the less air there is and gasoline evaporates rapidly, especially when it’s warm

    We haven’t found much of a consensus about whether gasoline evaporating from automobile gas tanks is truly “lost,” whether the amount of (hypothetical) loss is significant or negligible, or how much the evaporation rate would really be lessened by motorists’ driving with gas tanks never less than half full. Nonetheless, we can still make some rough economic estimates about the purported advantages of this tip.
    Some advanced gasoline filtration systems claim to recover about 2% of the fuel lost by evaporation from gas station storage tanks, so we’ll use that figure as a baseline for argument’s sake. (Yes, we realize that underground storage tanks and automobile gas tanks are two very different things.) In the scenario outlined for tip #1 above, our typical consumer might save about $62 per year on gasoline if he could completely eliminate losses due to evaporation from his automobile’s gas tank (and this tip only addresses reducing evaporation, not eliminating it).
    Is that savings really worth essentially halving the storage capacity of your car’s gas tank (thereby requiring you to stop for gasoline twice as often as before)? Assuming that our typical consumer bought gasoline once a week, and that the fill-up process averaged a modest 8 minutes (including the time to get to a gas station, to wait in line if the pumps are all busy, to pump the gas, to pay for the purchase, and to get back on the road), said consumer would be spending an extra 7 hours per year pumping gas to achieve these savings. Is that a good trade-off of time vs. money?

    When you’re filling up do not squeeze the trigger of the nozzle to the high setting. You should be pumping at the slow setting, thereby minimizing vapors created while you are pumping.

    The primary claim here is that service station pumps in some places use nozzles fitted with vapor recovery systems, but those systems recover and recycle vapors produced during the process of dispensing gasoline which the consumer has already paid for. (That is, the pumps do not adjust price or volume to reflect vapor recovery, so the consumer is essentially paying for losses due to “waste” even though the retailer is recouping those losses through a recycling process.)
    The efficacy of this tip is another issue of dispute. Advocates maintain that pumping gas more slowly produces fewer vapors, and therefore consumers get more for their money by using slower settings on pumps (because less gasoline is lost to vaporization). Critics (including state regulators) assert that the amount of vapor loss produced during the pumping process is so small as to be economically insignificant to the ordinary consumer. And, as in the tip #3 above, one has to consider the time factor: Is the aggregate amount of time you’re going to lose by using only the slowest delivery setting at every fill-up really worth whatever modest amount of money you might save?

    The bottom line is that there are much easier and better ways of improving the efficiency of your car (and thus of saving you money at the pump) than the tips outlined above. Particularly important is proper maintenance, including engine tune-ups, wheel alignments, tire pressure checks, and filter replacement. Mileage can also be improved by removing from the car little-used equipment that adds weight or increases drag (e.g., sporting gear, tools, roof racks/carriers). Driving habits are especially important: jackrabbit stops and starts eat up extra fuel, as does driving at higher speeds. All in all, the simple habit of engaging in planning and combining multiple trips into one excursion will likely save the average motorist far more money (and time) than all four of the above tips combined.

    Last updated:   7 July 2015

  5. “The California Energy Commission (CEC) advises that vehicles should be turned off if the expected wait will be longer than 10 seconds”.

    No way in Hell am I turning off the engine at a stop light! Road construction, yes. Almost anything coming out of CA is nuts. Just sayin’.

    • I agree with not turning your engine off for 10 second delays, but for a different reason. It seems logical, that it will take more fuel to start up after a 10 sec delay then you will save. If you are in traffic delayed for say an accident and you will not be moving for some time, then turn it off. But for for a traffic signal, that seems a little ridiculous……..

    • Slowing down the production has nothing to do wit whether or not a manufacturer is willing to allocate the resources for for better Quality control. If they are not doing it now, with maximzed profits, what makes you think that decreased profits will encourage them to build better rigs. They will simply take their profits and run.

  6. I agree with all the gas saving points but the last one, that used to be true when underground tanks were simply steel tanks buried underground. Today tanks are made with double wall insulated material the will not rust out and being double wall construction they are somewhat immune to temperature swings so the fuel will remain constantly the same temperature. A larger concern should be hot fuel as the fuel delivered to the filling station is generally hotter than ambient temperature which makes the fuel expand and after its inside you tank it cools then you have significantly less volume. Fuel suppliers are aware of this so when it is delivered to the retail station it is priced on a temperature compensated scale. Consumers are the ones getting screwed because when we fill our tank it’s not based on temperature but gallons going thru the pump.


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