Why Is My Gas Mileage So Good?

In a statement written by an agency of the Baha’i faith we read:

Writing to the political and religious leaders of his own day, Bahá’u’lláh said that new capacities of incalculable power – beyond the conception of the generation then living – were awakening in the earth’s peoples, capacities which would soon transform the material life of the planet. It was essential, he said, to make of these coming material advances vehicles for moral and social development. If nationalistic and sectarian conflicts prevented this from happening, then material progress would produce not only benefits, but unimagined evils. Some of Bahá’u’lláh’s warnings awaken grim echoes in our own age: “Strange and astonishing things exist in the earth”, he cautioned. “These things are capable of changing the whole atmosphere of the earth and their contamination would prove lethal”
Baha’i International Community, 1999 Feb, Who is Writing the Future?

Why is my gas mileage so good considering that I drive an SUV? My mileage figures never dip below 22.8 mpg and go as high as 29 mpg on long trips. In other words, I always get better than the EPA estimates for the model I drive, a Toyota Highlander Hybrid. The average SUV gets between 12 mpg (city) and 17 mpg (highway). I am taking these estimates both from the Consumer reports annual automobile issue and the EPA. Most SUVs have less total horsepower than my car has. Point by point, here are a few things that I do.

Air conditioning

According to Consumer Reports and my own observations, running your air conditioner will cost you a loss of about one mile per gallon. Rolling the windows down will create enough aerodynamic drag on the vehicle to cost you more than two miles per gallon. An overheated driver can easily become impaired so that is another consideration. Many contemporary cars have automatic climate control. In my car, I use the climate controls to set it to 70 degrees. My home is a different story altogether. I set the temperature at home to 80 degrees, which is reasonably comfortable. One reason why the revised Environmental Protection Agency (EPA) figures are a little more accurate is that they run a car’s air conditioning during part of their tests. That’s still not quite real world but it is more realistic.

A gem from Discover Magazine, June 2008: “Keep your windows closed at high speeds — drag from open windows can reduce a car’s fuel efficiency by 10 percent.” Here is another reference as part of an article titled Debunking Gas-saving Myths. Full article.

Cruise Control

Cruise control even at boulevard speeds always delivers better mileage. You should engage cruise control whenever there isn’t too much congestion. My car has a real time gas consumption gauge right in the center of the dashboard. My son’s large SUV has one also but it only emphasizes the discouraging truth of such a large vehicle. It lost so much value recently that he couldn’t get rid of it. Even a gentle temporary tap on the gas pedal can drop the car’s steady consumption rate at 45 – 60 mph down from better than 40 mpg to less than 20 mpg. That’s exactly what the figures are for the car I drive. Drivers who don’t use cruise control are constantly stepping on the gas pedal. After having made four cross-country trips this past year, I am reasonably sure that practically nobody uses cruise control except possibly the police.

I get practically the same mileage at 55 mph that I do at 70 to 74 mph. That’s probably because my car’s engine is simply running at the most efficient part of its torque range. This is the first car I ever owned without a tachometer so I can’t be sure. I can’t shift gears anyway because it has a continuously variable transmission (CVT). Not only hybrids have that nowadays. The computer shifts more efficiently through an essentially infinite range than I ever could shift by myself. A smartly programmed computer is also why some cars now get better mileage with automatic transmissions than with manual ones.

If you read your Owner’s Manual (hardly anyone ever does) you’ll find your car’s torque peak RPM. That’s where it’s very efficient. Until you get over about 70 mph you might be getting the nearly the same mileage that you do at 55 to 60 mph.

Fast Starts

Avoiding fast starts is wasteful; that’s a given. Cars that take a long time to approach the speed level or whatever level most traffic wants to drive at are wasting gas. Not only do they lug and thus wear their engines, they frustrate other typically impatient drivers who will inevitably pass them, sometimes recklessly, and thus the total carbon emissions are greatly increased. The same idea holds true on the highway but more emphatically. The slower drivers are directly causing more carbon emissions. When they drive below the flow of traffic in the middle or fast lanes (a frequent occurrence) the effect is even worse. A slow driver in a fast lane is often an indicator of impairment and is usually dangerous aside from causing an increased overall carbon footprint.

I learned to drive in California. Thus, I learned that safe driving means entering a freeway at or near the speed of oncoming traffic. The state of Washington has a number of unintelligently designed freeway entrances where you have to come to a full stop at the end of the entrance lane. Then you must make a desperate attempt to speedup to avoid a collision with oncoming traffic. I never adjusted to that. In Georgia, the law requires you to move into another lane to enable traffic to enter the freeway at a safe speed.

I drove from Seattle to near Macon, Georgia in 1998, a distance of 2875 miles (4600 km) in just over 70 hours. I never exceeded the posted speed limits by more than two or three miles per hour. Experienced cross-country drivers know that prolonged speeding causes extreme tension which produces rapid exhaustion and impairment. Cruise control not only gave me better gas mileage; it kept me from becoming exhausted so I needed fewer rest breaks. If 70 hours for such a long trip seems short to you, it really is not short at all. It means that I only covered 41 miles per hour. On a shorter cross country trip, an average of 50 to 60 mph is a good estimate.

Tire Pressure

Regarding tire pressure, the owner’s manual or glove box recommendations are rarely optimal for best mileage. In American cars, the recommended pressures are intended to give a soft “boulevard ride” which is wasteful for a variety of obvious reasons including tire wear and handling issues. If you have Firestone tires, ask a Firestone dealer what the pressure really should be and so on, Michelin, etc. Better yet, ask the service writers at your car dealership. They usually know what is really best and for most vehicles it will be one to three units higher than what the auto manual says it ought to be.

If you don’t do this yourself and drive to a gas station to do it instead (where it costs money) it won’t help you. That’s because your tires build up pressure within a few blocks after you get started. If you rely on your oil change place or dealer to correctly inflate your tires that won’t help either. By the time you get there, your tires will already have more than the recommended pressure from the heat buildup of driving. They are just as likely to bleed air from the tires so you’ll be worse off than when you started. This is very common at “quick lube” places. A pressure reading is only meaningful when the tires are cold and you haven’t driven on them. You should get about two miles more out of every gallon if you pay close attention to tire pressure.

Reference: Saving Gas The Easy Way.

Idling the engine

My car only idles for 30 seconds after a complete stop. It automatically restarts the engine after you’re going about 20 mph. If your car has a well-maintained battery and electrical system you can also do that. Just turn off the engine if you have an unusually prolonged stop.

Fill up at the discount stations rather than the brand names. They sell exactly the same gas and quality as everyone else but for a little less money. Another tip from Discover Magazine: fill your tank in the evening. Gas expands when it’s hot outside. Gas pumps measure gas by volume so if the temperature has cooled down you’ll get a little more gas for the same price. Several reliable sources consider this tip a myth and I cannot personally verify it anywhere.

One more item that many people overlook, tighten the gas cap! You can lose more than 30 gallons a year through evaporative leakage otherwise. Discover Magazine, June 2008, has startling statistics on the extent of that loss in the state of California.

Finally, Consumer Reports is no better than a rough guess and nowadays it’s less accurate in some cases than the recently overhauled EPA estimates. Case in point:
I drive a larger vehicle because I have to haul things including very large dogs.


What if it were impossible for cars and trucks to go faster than 60 mph?

Passing other vehicles even when necessary for safety would be very difficult. In addition, the ability to make emergency avoidance maneuvers would be compromised. Hill climbing would be difficult. I remember a VW that I owned briefly in the 1960’s. It had difficulty reaching 45 mph uphill on the highway and several times was nearly engulfed by large tractor trailers. It was totaled by a head-on collision with an equally underpowered paper-strong car so I was rid of that death trap. That calamity was providential. I was unhurt when a drunken teenager crossed the median and hit me but the car was wiped out. I saw him coming but could not speedup to avoid a collision. Braking would have caused a pileup with ensuing destruction from behind. There was a lot of space in front of me but I could not reach it because the vehicle had so little power.

In other words, there are many factors to consider. I find it noteworthy that luxury cars continue to advertise ever more powerful engines.

The Top Ten Polluting Cars

Forbes Magazine published a list of the top ten most polluting cars. Click for a complete list of the top ten (there are several models on each level).

The top ten list includes nine Mercedes-Benz models, two BMW models, and the Volkswagen Touareg, the Number One most polluting car on the American road. Inclusions of these models are not surprising: GMC Suburban, GMC Tahoe, GMC Yukon, and some Jeep models. The list also includes six SUVs that are Flex Fuel (gas or ethanol). There are no Japanese car models in the top ten. With the exception of the Ford F-150 and Lincoln Navigator, there are no other Ford models on the list.

I can’t help but wonder what twisted logic motivated GM to introduce a pair of three-1/2 ton Hybrids. I read that they command close to a $20,000 price premium over their non-Hybrid equivalents. Not only would there never be any possible payback but also the environmental cost just to manufacture one is staggering. It was only recently that American manufacturers learned how to make their own hybrids and stopped licensing the technology from Toyota. Maybe they saw the inevitable crisis at last because it’s hard to see what else might motivate new engineering. Who buys such behemoths? Often it’s simply retired empty nesters that cannot possibly need Jabba-the-Hut land barges.

“Although American consumers are becoming more aware of environmental issues, they’re a long way from choosing vehicles for purely altruistic ecological reasons. ‘By and large most people believe that they have a right, a God-given American right, to drive whatever car they want and can afford,’ says Dr. Charles Kenny, a psychologist and president of The Right Brain People, a psychology research firm based in Cordova, Tenn. ‘Americans still have a love affair with their vehicles, which are associated in their minds with freedom and independence.'”

The reason gas prices are so high are many including but not limited to the incredibly high cost of a useless war, government unwillingness to promote alternative energy, runaway profit taking by the oil companies, dwindling supply in areas where it still makes sense economically or is environmentally safe to drill, and a host of others.

Each time I’m in Atlanta I am amazed at how fast people drive. Driving 15 to 20 miles over the speed limit is typical. Atlanta has some freeways that are as broad as 14 lanes wide in places. People speed even in the “slow” lanes. Pickup drivers and tractor-trailer drivers are the worst offenders. You see Sheriff Bubba lying in wait in speed traps all over the state but not in Atlanta. That is one of the significant reasons the Atlanta area is so heavily polluted.

Interesting sidebar: Crude oil does not come from decaying dinosaurs. That’s a fable spread by Evangelicals who think dinosaurs all died because of a world-encompassing flood 4000 years ago. Oil is actually composed of zooplankton and algae. They believe that since we’re only going to be here for a short time until the rapture comes that it makes perfect sense to use up every resource. Evangelicals are one of the major voting blocks in the US.


Eventually, fossil fuels will go the way of coal and steam fired engines. Won’t that make a large difference?

Yes, they have to do that. Not only are there sustainability issues but the pollution from fossil fuels now endangers the entire planet. Pollution threatens mass species extinction, loss of human habitats in coastal areas, and mass famines. The mad rush to “Americanize” in China will add tens of millions of new cars and thus accelerate the ongoing environmental catastrophe and hasten the tipping point. I believe the tipping point is inevitable.

Another interesting thing: the Northern hemisphere might not continue to get warmer. After the tipping point, it will get a lot colder due to the shutdown of the “ocean conveyor” and coming changes in the jet stream. Both of them control the weather of the Northern hemisphere. If the growing season shortens dramatically then crops will fail. Eventually that will lead to the same deprivations that are accelerating in Africa.


Scientists are finding efficient ways of turning plant waste materials into biofuels instead of using food crops. Why isn’t that being done now in the US to any meaningful extent?

As long as agribusiness giants who dominate the American cornfields (Archer Daniels Midland is one) together with oil interests underwrite the US legislative and executive branches, that will not occur.


Won’t higher fuel prices encourage conservation?

Obviously higher fuel costs impact the poor the most and the rural poor the most. Well-intentioned liberal thinkers who want to tax us into conservation and artificially boost the price of fuel even higher are totally disconnected from the poor and their needs. They drive their polluting diesel Mercedes and gas guzzling SUVs around big cities and remain as clueless as everyone else. If the US wasn’t spending a trillion dollars on a meaningless and destructive war, they could subsidize the price of fuel for the poor. Meanwhile the push for corn-based ethanol, a fuel whose production emits more pollution than it will save, drives up the price of food dramatically higher.

A Toyota Prius is manufactured at a high cost to the environment because its batteries (not to mention plastics and other materials) are highly toxic. The pollution lands in China, the manufacturer of the batteries and the source of its raw materials, where the rest of us don’t have to think about it. Prevailing winds from Asia drop the pollution they carry all over the American West the next day and every day after that. The Chinese government is as shortsighted about pollution as the US government and the giant oil companies. The enormous consequences of pollution and the staggering annual loss of lives it causes in China are well documented.

Recall the quote from Baha’u’llah that opened this essay: “These things are capable of changing the whole atmosphere of the earth and their contamination would prove lethal.” It can also refer to the consequences of environmental pollution rather than only as a reference to nuclear power and weapons. I have never read that implicated and additional meaning in any authoritative Baha’i text. It is purely an assumption on my part to extend the meaning because it makes practical sense.

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  1. Steven · July 15, 2008

    The main thing I question is a blanket statement that “…running your air conditioner will cost you a loss of about one mile per gallon. Rolling the windows down will create enough drag on the vehicle to cost you more than two miles per gallon.”

    I think it depends on how much you run your air and how far down the windows are rolled. Don’t have data to generate a graph or anything but seems physically sound that air conditioning running on the lowest fan setting takes less power and running with windows down at 35mpg is less a drag than doing it at 75mph and in parallel running with the windows down half way is less drag than running all the way down….

  2. Steven · July 15, 2008

    how about filling your tank only half way or so – so the rest of the full tank isn’t dead weight that has to be accelerated??

  3. Dave · July 15, 2008

    Re: “fill your tank in the evening. Gas expands when it’s hot outside. ”

    I think this may be wrong on the face of it because generally the night air cools until around dawn, at which point the air warms until sun down. This would imply that the best time would be early in the morning.

    The reason that any effect would be small is that the storage tanks are in the ground where the temp does not vary much. The thermal inertia of the fuel is good enough that any effect would have to be due to warming in the above ground equipment as the fuel flowed.

  4. Mathew James · August 11, 2008

    Great post, it was very informative. I think its a must read.

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