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(DV) Garcia: Fuel Conservation and Sustainable Mobility







Fuel Conservation And Sustainable Mobility
by Manuel García, Jr.
September 23, 2005

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A key motivation for the Iraq War must certainly be the desire of American policy planners to secure petroleum reserves with which to fuel the American military in the 21st Century. American armed forces are all about mobility and global reach, and they require a tremendous quantity of fuel for all that high-speed, long-distant and low miles-per-gallon mobility. Without liquid hydrocarbon fuels, there is no "superpower" military, and without that there is no American empire. Petroleum is the lifeblood of the American war machine.

The American consumer, as well, has an unquenchable thirst for petroleum, using it in large inefficient automobiles, luxury trucks, and recreational vehicles of many kinds. Reducing America's desire for oil would help rein in American imperialism and aggression. Any such reduction is unlikely to occur in the military, by the very nature of its purpose. So, Americans opposed to the Iraq War and American imperialism favor a significant reduction in the civilian consumption of petroleum, most particularly as gasoline fueling transportation.

One step many individuals can take immediately is to reduce their own use of gasoline: drive slower, and take mass transit. Were such personal economization the rule rather than the exception, we could free ourselves from many unsavory foreign entanglements and much unwholesome foreign policy, and we could free considerable national resources, now wasted in the military, for major domestic improvements. We will not soon invent miracle technologies to liberate us from oil -- super-hybrids, hydrogen fuels (, and the like -- and that outperform a national consensus for fuel conservation.

Let's consider automobile fuel economy, and some thoughts about sustainable means of personal mobility.

In a recent e-mail bulletin to the CERJ distribution (John Woolman College of Equity-Restorative Justice,, John Wilmerding ( made a case for driving at lower speed to improve automotive fuel economy, along with safety. John noted several points about automotive fuel efficiency, and cited three web sites, summarized here.

An experiment documented here notes:

"[S]peed was found to have the greatest, most consistent effect on gas mileage. The factor of air resistance tends to increase with the square of one's speed, therefore the air resistance generated while traveling 65 mph will be twice that generated traveling at 45 mph. This has a substantial effect on how hard your engine must work and consequently the gas mileage of the vehicle."

"... note the optimal gas mileage around 45 mph. The idea behind getting the best possible gas mileage is simple; have your tires rotating as fast as possible simultaneously while your engine works the least. Theoretically, this is the speed that your vehicle is traveling just as it shifts into overdrive, or fifth gear in a manual."

Using a Honda Civic Hybrid, the experimenter in this study measured:

60.9 mpg (no cruise control, 55 mph)
57.9 mpg (no cruise control, 65 mph)
55.2 mpg (cruise control, 65 mph)
49.3 mpg (cruise control, 70 mph)
48.0 mpg (cruise control, 70 mph + 200 lbs.)

Comparisons among these results include:

6.24% improvement in gas mileage driving at 55 mph versus 65 mph,
10.9% improvement driving at 65 mph versus 70 mph,
19.2% improvement driving at 55 mph versus 70 mph
3.33% improvement driving 65 mph without cruise control vs. 65 mph with cruise control,
2.44% improvement driving at 70 mph without weight vs. 70 mph + 200 lbs.

The Environmental Protection Agency's Fact Sheet OMS-17 of August 1994, also advocates reducing speed for higher efficiency, stating "Avoid high speeds. You can improve your gas mileage about 15 percent by driving at 55 mph rather than 65 mph."

The US Government web site on fuel economy states:

"Aggressive driving (speeding, rapid acceleration and braking) wastes gas. It can lower your gas mileage by 33 percent at highway speeds, and by 5 percent around town. Sensible driving is also safer for you and others, so you may save more than gas money. Fuel Economy Benefit: 5-33%. Equivalent Gasoline Savings: $0.15-$1.01/gallon."

Also, "While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph. As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.21 per gallon for gas. [These] cost savings are based on an assumed fuel price of $3.07/gallon."

The Canadian Broadcasting Company concurs with these findings, noting that, "Speeding will also cut into your gas mileage. Increasing your cruising speed from 100 km/h to 120 km/h will drive up fuel consumption by about 20 per cent. Reducing your speed from 100 km/h to 90 km/h improves fuel economy by about 10 per cent."

Finally, after presenting his evidence, John concludes his bulletin with a challenge to his readers, "If there is anyone out there with proof that European autos of the same size and weight get roughly twice the gasoline mileage of US ones, I'd like to see it."

Let's consider the effect of engine size first, and then discuss mass transit.

European and Japanese automobiles of comparable weight and size to American vehicles can get much better fuel economy when they use engines of half to one-third the capacity of US engines.

Because American cars are generally larger, comparable foreign vehicles would be "larger" ones (like the Japanese cars we are accustomed to seeing, but with the "standard" or "economy" engines, not the "de lux" or "sport" versions), and they should be compared to "smaller" US cars. Most people outside the U.S. who drive cars (as opposed to bicycles, scooters, motorcycles and motorcycle-engined carts) will be propelled by engines of under 2 liters. For "the same weight and size" one will see much slower acceleration, and lower ultimate top speed. Also, at a given speed comparable to that of Detroit iron, less air and fuel will be used.

US automobile engines are generally over 2 liters. US eight cylinder engines are usually 5 liters or more (the small block, Chevy 283 cubic inch V8 engine is 4.6 liters; 305 cubic inches equals 5 liters). Power is fun, so since the '60s engine size has gone up in foreign cars (for foreign use), as well. However, it is still true that these vehicles have smaller engines and weigh less on average than US vehicles. A reasonable comparison would be between small foreign trucks and delivery vans, and US passenger "cars" at their largest, our SUV gentrified trucks. What you would find is that given equal size and weight, the foreign trucks would have smaller engines, higher efficiency, and lackluster acceleration. Any American SUV with a four cylinder 1.5 liter engine would be a very efficient car -- not fast or quick, but efficient; probably with a top speed of 70 or 80 mph, and good acceleration up to 30 mph. From 30 to 70 mph, however, would be a very leisurely progression. Anyone who ever drove an old VW minivan might understand the type of driving involved.

Much, maybe half or more, of the petroleum blown out as smoke by US cars goes for quick acceleration, and idling in traffic jams -- hurry up and wait. During the gas crisis of the 70's, a magazine called Mother Earth News put out articles showing how to convert 8-cylinder engines to 4-cylinder, by properly removing half the spark plugs and blocking fuel delivery to the inactivated cylinders. This halved the capacity of the engine, obviously boosting fuel conservation; the open plugholes vented the air pressure in the four dud cylinders, and reduced the resistance of the engine to turning the crankshaft.

Also, in any vehicle, reducing the number of powered accessories (and removing them to save weight) reduces the need for power from the engine, and saves fuel. A manual transmission is one such economizing measure. While it is true that cruising at 45 mph will optimize fuel economy (short of not going at all), one might still like to travel faster. Also, unless one is racing for sport, one would not wish to be constrained by an aerodynamic and slim profile, but would want some capaciousness for passengers and cargo. So, the engine needed to keep up a cruise speed of 70-80 mph might have to produce perhaps 80 horsepower, to overcome mechanical inertia (move pistons, crank, transmission and differential gearing), friction, and then the air resistance. An engine that produces only 80 hp (say a 1.6 liter with 50 hp/liter, race cars are usually >100 hp/liter) would have little extra oomph to accelerate a large vehicle.

But, making a bigger engine to provide that acceleration means that at all times and for all speeds one calls on more capacity of air being pumped through the engine (car engines are air pumps), and with the necessary fuel-air mixture (maybe 1:16) there is relatively more fuel being used every second of operation -- one pays for the capability to accelerate. It is this capability that is the culprit when it comes to America's excessive use of motor fuels. "Pedal to the metal" has its price, including the Iraq War.

Beyond eliminating this "need" for quick getaways, additional savings in fuel can be had by reducing time spent in idle traffic, that is to say developing and using mass transit.

I suspect that much of the motivation for producing hybrid vehicles today is:

1. industry's desire to continue producing high-priced vehicles (profits), and
2. consumers' desire to continue using quick-accelerating vehicles.

I own a 1993 Ford Escort station wagon; this is largely a Mazda 323 re-styled by Ford, who owned a major portion of Mazda at that time. The engine is 1.9 liters, and the trunk space is identical to the Ford Explorer (an SUV) of the same year -- you may recall the Explorer was a very "hot" seller. The Escort gets 30-37 mpg, depending on how it is driven, and I have gotten close to 36 mpg with an average speed over 70 mph, in highway driving. The Explorer gets about half this fuel economy.

In 1994, I took two children and my wife to Baja California, where we went off-road, across streams (very gingerly, believe me), onto dunes, and camped out for 3 weeks. The Escort is a simple front-wheel drive car, without extreme ground clearance. "Off road," we drove the way the Mexicans do -- very slowly. With a full load, including a mound of stuff strapped onto the roof rack, we got about 33 mpg over the 2000-mile odyssey. I often went 80 mph to make time down the Baja highway (Baja is long!). In 1993, the Escort was one of the lowest pollution-emitting line of cars sold, perhaps the lowest. I like sports cars and fast driving (which is why I went into engineering), so I often drive my Escort past slow pokes in big Detroit iron, even Corvettes. With little load, the Escort has sufficient acceleration for typical US driving. It is clear that were this car to sacrifice 20 percent of its engine capacity and power, say to a 1.5-liter motor, I could have a vehicle (with manual crank windows and manual transmission) that could probably achieve over 40 mpg. This is typical for today's hybrids, and my wife's 1981 ~1.3 liter Datsun 510 got close to this.

But hybrids use batteries in addition to a 1.5-liter to 2-liter engine, to keep enough power on tap for the luxuries, the weight, and the acceleration people want. All that costs a lot of money -- hybrids are for the elite, they are not transportation for the masses.

To me, the car of the future would more likely be like the Fiats and Peugeots and Minis of the late 50s and early 60s, better designed for crash-worthiness, better smogged, with fuel injection instead of carburetors (for precise fuel metering, aiding both power and pollution control), with manual windows and transmissions, and with 0.8-liter to 1.6-liter engines. Fuel economy would be around 50 mpg, and afford-ability and reliability would be excellent. Such cars would be the people's car, the "volkswagons" of the Hubbert downslope.

Complimenting such a fleet would be a nationally maintained public transportation system, integrating road (bus), rail, aero and boat transportation. Also, all metropolitan areas ("cities") would have extensive trolley (electric light rail, electric bus) networks that would be free (no fares) in all "downtown" areas, making it possible to limit motor vehicle traffic in urban centers. These free rail trolleys and trolley buses would operate like any escalator or elevator -- one simply boards and moves on. The "cost" of this service would come from fuel savings and as the reduction of pollution and its related costs, as well as the national subsidy of mass transportation (which would include a social component, as being a part of the "safety net" for the poor).

This model is routine on many large government sites, university and industrial campuses, military bases and airports. Personal motor vehicles (and even cargo vehicles) are parked at the periphery, and modes of mobility within the site are provided. Besides reducing congestion and smog, this allows the thoroughfares to be relatively free of obstacles to emergency vehicles responding to calls for security (police), fire or medical emergencies. It can also enhance the experience of being a pedestrian.

No doubt, some will argue implementing such a system in America's cities (and into their outlying suburbs) would gore someone's ox, say those capital interests now making handsome profits in fuel and transportation industries geared to the present style of mobility. But I am not concerned with that; the profits for the few must give way to the benefits for the many. The primary benefit, here, being the preservation of a livable earth, and the sustainable continuation of equitable arrangements for our mobility.

Manuel García, Jr. is a working physicist and amateur poet. He can be reached at

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