230 miles per gallon
An essay I wrote two decades ago, newly relevant as the Iran war constrains world oil supplies and sends fuel prices soaring.
The original Canadian version in 2005 was metric (one liter per 100 kilometers), but this 2007 revision was awkwardly translated into avoirdupois in an unsuccessful attempt to get it published in the US. Oil prices were relatively high in that era, and I think the key messages of the essay remain valid. I was inspired to resurrect the essay by Paul Krugman’s Substack post today (March 22, 2026), “How to Burn Less Oil.”
230 miles per gallon
We can and should reduce our motor vehicles’ fuel consumption, but the biggest challenges and changes could turn out to be behavioral
By Robert Bott
- co-chair, Calgary Alternative Transportation Co-operative (CATCO), a carsharing organization
- author, Our Petroleum Challenge (Centre for Energy Information, 2004)
- based on a talk, “The Past, Present and Future of the Automobile,” June 30, 2005, Fort Calgary, during Calgary Architecture and Design Week
Chartered buses carry an average of about 33 passengers, and the average bus goes seven miles on a gallon of diesel fuel. On a per-passenger basis, the chartered buses’ fuel consumption works out to about 230 miles per gallon. Among people-moving modes, that’s about as good as it gets.
School buses, scheduled bus lines and urban transit buses carry fewer passengers on average than chartered buses, but generally get between 100 and 160 passenger-miles per gallon – which is comparable to, or somewhat better than, most non-electric passenger rail systems. Air travel averages 67 passenger-miles per gallon of jet fuel. By contrast, the average private motor vehicle in North America gets 20 miles per gallon of gasoline and carries 1.6 people, for fuel economy of 32 passenger-miles per gallon.
The averages conceal huge variations. A gasoline-electric hybrid car supposedly can get 58 miles per gallon under ideal conditions; with four seats occupied, it would be as fuel-efficient per passenger-mile as the average chartered bus. Single-occupant pickups, SUVs and vans in urban traffic can consume up to 30 times that much fuel per mile. Near-empty planes, trains and buses are wasteful too.
Why do we put up with so much inefficiency? Local and regional air pollution and greenhouse gas emissions should be sufficient reasons to spur change, and the linkages between Iraq and oil and motor vehicles should be obvious. Yet somehow these collective concerns fade into the background when individuals make choices - where to live and work, what vehicle to buy, when and how much to drive, which politicians to elect.
The average annual cost of owning and operating a motor vehicle in the United States is about $8,400, but fuel generally accounts for less than 20 per cent of this, so higher gasoline and diesel prices have a relatively small impact. The huge costs of building, maintaining and policing roads are hidden in taxes from all levels of government. Other costs are dispersed and incremental -- health impacts of vehicles’ pollution and accidents (more than 10 times as many deaths per passenger-mile compared to bus, train or air travel), the decline in exercise and fitness, the time spent in traffic and no longer available for family and community activities. The full costs are seldom weighed objectively against the allure of seemingly unfettered mobility.
As a result, we continue to sell, buy and license vehicles that can go more than twice the maximum legal speed limit. Vehicle manufacturers, advertising agencies and the media continually promote unsafe, illegal and wasteful behavior -- just watch the ads, or read the reviews of the many car and light truck models currently available with more than 400 horsepower, enough to haul a loaded semi-trailer. If horsepower in car engines had stayed at 1990 levels, the current models would be at least 33 percent more fuel-efficient. As to the SUV boom, suffice it to say that 85 per cent are never driven off-road.
Although four out of five North Americans now live in towns and cities, our geography, climate, economy and current urban design suggest that personal motor vehicles will be with us for a long time to come. The good news is that our existing vehicles and related systems are so inefficient that it will be possible to make big reductions in fuel consumption and emissions when we are forced to change or decide to do so.
In the search for greener alternatives, gasoline-electric hybrid vehicles get most of the attention and seem certain to continue gaining market share. The current hybrid technologies reduce fuel consumption at least 10-25 per cent for any given vehicle type and use. Variations such as diesel-electric hybrids and plug-in rechargeable hybrids could offer further improvements. The Mercedes Smart car, with its tiny diesel and six-speed transmission, may be a harbinger of future urban commuting vehicles; Volkswagen has built an ultralight prototype vehicle that actually goes 230 miles on a gallon of diesel. Bear in mind, however, that diesel fuel contains 14 per cent more energy per gallon than gasoline and produces 16 per cent more greenhouse gas emissions.
Ethanol and biodiesel fuels meanwhile can help to reduce both petroleum dependence and emissions. In polluted cities, clean-burning natural gas is an attractive option for high-use vehicles that can be refueled frequently. Electricity could play a bigger role in the future too. Off-peak electricity from renewable or nuclear sources could, for example, be used to recharge all-electric vehicles or plug-in hybrids and to run compressors for refueling natural gas vehicles. One innovative car design (www.theaircar.com) uses compressed air to store energy. If hydrogen fuel cells prove feasible for vehicular use, electricity will be needed to produce and compress the gas.
It is a mistake, however, to focus too much on vehicles and energy sources. It takes years for a new technology to prove its merit, and more years to build the necessary manufacturing facilities and support systems. The average vehicle stays on the road for 15 years, so even if a breakthrough technology were in the showrooms today and everyone bought it, we would have to wait seven or eight years before half the fleet would be converted. Moreover, just improving the vehicles does not address the social costs. A hybrid stuck in traffic may not be polluting but it is still wasting the occupants’ time and energy, exposing them to safety hazards, and taking up valuable space in the urban landscape.
Three options with more immediate payoffs are carsharing, carpooling and telework:
· Carsharing (a form of locally based car rental) reduces the number of vehicles on the roads and encourages users to plan trips carefully and to consider alternatives such as walking, biking or transit. On average, carsharers reduce annual miles driven by 50 per cent compared to private vehicle ownership.
· Carpooling increases vehicle occupancy and per-passenger fuel efficiency and reduces rush-hour congestion and pollution.
· Even one or two days a week of telework (using telecommunications to work from home or a neighborhood work station) can have a significant impact on cumulative fuel use and emissions.
I estimate that I have reduced my transportation fuel use and related emissions more than 50 per cent since 1994 by using a combination of these three methods. I save more than $3,000 a year and get a lot of healthy exercise from walking and biking.
Not everyone can or will take advantage of such options, though, and it is entirely possible that real energy shortages, unbearable traffic congestion or pollution crises will soon require more draconian measures. In that case, attention will focus on one simple fact, i.e. that motor vehicles operate most efficiently at a speed of about 50 miles per hour. Above that speed, more than half of the engine’s power goes to overcoming air resistance, which increases with the cube of velocity, and at lower speeds disproportionate energy goes into internal friction and operating systems such as lights, stereo, heating or air conditioning.
Our present situation seems almost designed for inefficiency - vehicles alternately roaring along at more than 70 mph or inching along under 15 mph, and either way using 20 per cent more fuel than at 50 mph. Continual accelerations and decelerations also shorten the life of brakes, tires and engines, and add to the safety hazards of motoring. The first response to a real energy crisis could and should be lower speed limits and widespread use of photo radar. When speed limits were lowered during the perceived energy crises in the 1970s, fuel consumption dropped 10 per cent.
The converse challenge, preventing the 15 mph crawls and gridlocks, is difficult but not impossible to address. Demand-rationing measures include downtown entry fees, parking restrictions, high-occupancy-vehicle lanes, and road tolls. The city-center “congestion charge” in London, England, equivalent to US$15.42 per entry (7 a.m. to 6 p.m., Monday to Friday), was imposed amid great trepidation but seems to have eased traffic clogging considerably. Peak-smoothing options include flexible or staggered work hours and better electronic traffic control (e.g., signage and broadcasts directing motorists onto less-congested routes). Making these measures responsive in real time - e.g., a $20 toll if the road is overcrowded, $1 if empty - could make them much more effective.
Another way to improve efficiency – one that should please truckers and cyclists too -- is to maintain our roads better. A rough, bumpy or potholed road can easily increase fuel consumption 10 per cent or more compared to a smooth, hard surface. (The low rolling resistance of steel on steel is the key to the freight-hauling efficiency of railroads.) And there are lots of simple things individuals can do – driving conservatively, keeping tires properly inflated, turning off the engine when stopped in traffic, regular tuneups and lubrication -- that can add up to significant savings.
One of these days, we might actually start to design cities for people rather than cars. The turning point will probably come when governments and developers take a hard look at the way parking spots are mandated, priced and sold. At present, commercial and residential developers are usually required to provide a certain number of parking spaces for each unit. The cost, which can easily reach $50,000 per space in larger cities, is then incorporated into the selling price or rent. If this requirement were relaxed and the parking spaces were sold or rented separately from the unit, many buyers or tenants might decide they would sooner rely on walking, biking, public transit, carsharing and/or carpooling.
Carsharing is well-established in Europe and gaining momentum in North America. As of January 1, 2007, 18 U.S. carsharing programs claimed 134,094 members sharing 3,637 vehicles, and in Canada 13 organizations had 21,817 members sharing 994 vehicles. The advantage of carsharing is that it reverses the relationship between fixed and variable vehicle costs. In conventional vehicle ownership, most of the costs are fixed -- vehicle purchase, finance, insurance, license, etc. -- while the per-mile costs of fuel, lubrication, tires and incremental maintenance are fairly low. In other words, the more you drive, the less each mile costs on average. A carsharer’s costs, by contrast, are directly proportional to miles and hours of usage.
An often-overlooked major player in transportation, the insurance industry, could helpfully advance the user-pay principle much further. Progressive Insurance introduced its “Trip Sense” program in Minnesota in 2004 and recently extended it to Michigan and Oregon. This usage-based insurance offers drivers discounts up to 25 per cent based on data from an onboard “black box” that records how much, how fast and at what times the vehicle is driven. This might be the first step in a real revolution. Some commercial fleet operators already use geographic positioning and information systems so accurate that they can tell if a driver speeds in a school zone. Insurance based on such data could have far-reaching impacts on highway safety and health costs as well as on fuel efficiency.
From there, it is not a big leap to integrated systems that assess and display the full economic, social and environmental costs of vehicle use as they are incurred. The mellow androgynous voice emerges from the dash: “Sorry, sir or madam, that last acceleration exceeded your credit limit. Please pull over before your vehicle is disabled. A bus will be along shortly.” Rather than wait for the bus, you might pull a folding bike out of the trunk. I have calculated that my bike would get more than 1,000 miles per gallon if the calories in food and sports drinks were converted to the equivalent-equivalent amount of gasoline.
Motor vehicles are going to change, perhaps in ways we cannot foresee, but the bigger changes may turn out to be in how, where and when we use them.
Robert Bott is a Calgary-based writer, editor and consultant specializing in energy and the environment.