Building on a previous post on the energy efficiency of various foods, I decided to create a list of transportation modes by fuel efficiency. In order to compare vehicles with different passenger capacities and average utilization, I included both average efficiency and maximum efficiency, at average and maximum passenger loads.
The calculations and source data are explained in detail in the footnotes. For human-powered activities, the mpg ratings might appear high, but many calculations omit the fact that a human’s baseline calorie consumption must be subtracted to find the efficiency of human-powered transportation. I have subtracted out baseline metabolism, showing the true efficiencies for walking, running, and biking.
For vehicles like trucks and large ships which primarily carry cargo, I count 4000 pounds of cargo as equivalent to one person. This is roughly the weight of an average American automobile (cars, minivans, SUVs, and trucks).
The pmpg ratings of cars, trucks, and motorcycles are also higher than traditional mpg estimates, since pmpg accounts for the average number of occupants in a vehicle, which according to the Bureau of Transportation Statistics is 1.58 for cars, 1.73 for SUVs, minivans, and trucks, and 1.27 for motorcycles.
List of Transportation Modes By Person-Miles Per Gallon (PMPG)
| Transport | Average PMPG | Max PMPG |
| Bicycle [3] | 984 | 984 |
| Walking [1] | 700 | 700 |
| Freight Ship [10] | 340 | 570 |
| Running [2] | 315 | 315 |
| Freight Train [7] | 190.5 | 190.5 |
| Plugin Hybrid [5] | 110.6 | 350 |
| Motorcycle [4] | 71.8 | 113 |
| Passenger Train [7] | 71.6 | 189.7 |
| Airplane [9] | 42.6 | 53.6 |
| Bus [8] | 38.3 | 330 |
| Car [4] | 35.7 | 113 |
| 18-Wheeler (Truck) [5] | 32.2 | 64.4 |
| Light Truck, SUV, Minivan [4] | 31.4 | 91 |
[0] I used these conversion factors for all calculations.
[1] Walking: A typical person expends roughly 75 calories to walk a mile in 20 minutes. An American burns about 30 calories just to exist for 20 minutes, so the net expenditure for walking is 45 calories per mile. One gallon of gasoline contains roughly 31,500 kcal, so 45 calories is 0.0014 gallons of gas. Thus the average American has a walking efficiency of 700mpg. This estimate is higher than that given elsewhere – the crucial difference is that you have to subtract out baseline metabolism, since an American consumes over 2100 calories a day just to stay alive.
[2] Running: The calculation is similar to [1]. Here we assume a 6 minute/mile pace, which burns 1088 calories per hour, or 109 calories per mile, and 100 net calories per mile. 100 calories is 0.003 gallons of gas, for a fuel efficiency of 315mpg.
[3] Bicycles: Bicycling at 10mph requires 408 calories per hour, or 40.8 calories per mile, which is 32 net calories per mile. This yield an mpg rating of 984, higher even than walking!
[4] Automobiles: The Bureau of Transportation Statistics has done the heavy lifting for us, calculating BTU per passenger-mile for cars, light trucks, and motorcycles. For cars, the latest (2008) data point is 3501 BTU / passenger-mile, or 0.028 gallons per passenger-mile, which equals 35.7 pmpg (BTS assumes 1.58 passengers on average, so this equates to 22.6 mpg). Using the same BTS data, average pmpg for light trucks is 31.4, and for motorcycles is 71.76. For max pmpg, we use a max passengers of 5 for cars and trucks, and 2 for motorcycles. To do this calculation from the BTS data, we first divide the avg. pmpg by the avg. passenger count, and then multiply by the max in each case.
[5] 18-Wheelers: For 18-wheel rigs, BTS data shows an average diesel mpg of 5.1. This equates to a gasoline mpg of 4.6, using 125,000 btu / 138,700 btu as the gas / diesel energy ratio. The weight limit for trucks on most roads is 80,000 lbs, of which 55,000 might be the max load given a truck weight of 25,000 lbs. To convert load to passengers, I assume 4000 lbs per passenger, since that’s roughly the weight of a passenger vehicle. A 50% (average) loaded truck counts for roughly 7 passengers, and a full load counts for 14. Using these factors, average pmpg is 32.2 and max pmpg is 64.4.
[6] Plugin-Hybrids: With the exception of the Prius Hymotion conversion, plugin hybrids like the Chevy Volt have yet to reach market, and have not yet had a final mpg designation. Consumer Reports achieved 67 mpg with the Hymotion Prius, though Hymotion and many owners claim 100 mpg is possible. Using 70 mpg, and adjusting this by the 1.58 average passenger count, the Hymotion Prius has an average pmpg of 110.6, and a maximum pmpg of 350.
[7] Trains: While all trains have similar underlying efficiencies, passenger trains in the US are much less efficient in practice because of poor utilization. BTS calculates Amtrak efficiency at 1745 BTU per passenger-mile, which equates to 71.6 pmpg. Amtrak traveled 267 million car-miles in 2007, which equals to 16 billion potential passenger miles if the average car holds 60 passengers. In 2007 Amtrak consumed 10.5 trillion BTU of fuel, or 659 BTU per available passenger mile. Amtrak’s max pmpg is therefore 189.7 (if somebody would just ride it).
Freight trains consume 328 BTU to move a ton one mile. Using 4000 lbs of freight equals one passenger, this equals 656 BTU per passenger-mile, or 190.5 pmpg.
[8] Buses: At average passenger loads, buses achieve 3262 BTU per passenger-mile, or 38.3 pmpg. Per BTS data, buses average 6.1 diesel mpg, or 5.5 gas mpg. With a full load of roughly 60 passengers, a max pmpg of 330 is possible. The huge difference in average and max pmpg implies that buses are usually almost empty – perhaps smaller mini-buses should be used by more fleets.
[9] Airplanes: Airplanes flying domestic routes average 2931 BTU per passenger-mile, or 42.6 pmpg. The overall domestic load factor in 2008 was 79.6%, so at max capacity a plane might achieve 53.6 pmpg.
[10] Ships: In a previous post I found that shipping over water (by barge) costs one-third of shipping by rail. This implies that water based shipping is also roughly triple the efficiency in energy terms, since energy is one of the key cost drivers in transportation. This provides a rough estimate of 570 pmpg. According to this post, the world’s largest container ship travels 28 feet on a gallon of residual fuel oil (149,690 BTU or 1.2 gallons of gas). This equals 0.004 mpg. Per Wikipedia, the ship can carry 11,000 14-ton containers, or 77,000 passenger-equivalents using our 4000 lb conversion rate. Thus pmpg is 340 for this ship.
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Your numbers on human powered transportation are off an order of magnitude. At least in the USA where our food system has about 10 calories in to 1 calorie of output. Was the energetic cost of tires and bikes and shoes added in? For cars was the energetic cost of production and maintenance factored in. One other point, I did read a study where is you calculate the energy costs of roads and highways that current total nation fuel consumption for transportation is only about 50% of the entire energy cost.
The calculations helps me understand the fuel economy of various modes of passenger travel and how efficiency and carbon intensive they differ from each other. I figure the mode of transportation we choose can have a big impact and it can also affect time, cost, convenience and other factors. But all are indispensable to the growth our economy. According to U.S. Energy Information, almost 18 billion gallons of jet fuel were consumed in the United States, and the reason for that people cannot walk from the U.S. to Canada and therefore we need a different mode of transportation for that. We will continue to have many cars on the road and many people will use then, therefore, the EPA needs to remain focus on the Ethanol blend and promote higher level-blend as quick as possible. For example, EPA should allow E15 year around and give support car manufacturers to build more Flex-Fuel vehicles compatible to E85. Jef fuel from raw material like sugarcane, miscanthus, soybean and other organic matters are great ways for the U.S. agencies EPA and DOE to invest and promote cleaner and renewable fuels for our modes of transportation.
I’d love to see this list updated with the advent of fully electric vehicles.
The info should have been marketed as being for US as most numbers are derived from us data. The effort on attaining the max airplane figure was done poorly in my opinion. It only used domestic flight data, which likely lowers the numbers since US domestic flights are likely shorter duration than all US involved flights for example. Most other methods assumed a max number of passengers, here rather they calculated the max based on an entire fleet capacity average data, rather than looking at the most efficient aircraft type. Some planes are decades old. The plugin hybrid data is for only one vehicle model and they rounded up the mpg before calculating. Why? This means the above list is not reliable for comparing say max airplane to max plugin hybrid as the max values are not really the max values the average person would expect to have been reported. I do applaud giving the methods so we can see the flaws or limitations of the numbers.
I am a keen cyclist and user of well built cars that cover many miles from new. As an airline pilot though I would like to suggest that the figures for mpg per passenger are now at about 90 mpg according to the fuel figures that i use daily in my Airbus A320. I would be happy to supply figures for you to check if you wish, but I know from practice that aircraft have become a lot more efficient over the last few years and I think it’s time for a review?
Thanks, very good post. Keep this sharing.
Everything is very open with a clear explanation of the challenges.
It was really informative. Your website is useful. Thank you for sharing!
If freight ships are included, then pipelines should be considered as well, since they are very efficient in terms of moving material.
Gear analysis! Can you include the hoverboard please. Not the floating one, the hands free Segway one. What about Segway too. Or Rollerblade and Longboards skateboards.
What about for helicopters?
You need to account for the different speeds of these vehicles. How would a car compare to a plane if it was driving at 700 mph? Don’t forget to take atmospheric density into account! How much fuel would a ship use if it got up to 60 mph? Or 75 mph?
Take the typical calorie burn of a cyclist at 5 mph, 10 mph, 20 mph… and project that out for even higher speeds and see if they still come out ahead. Wind resistance does not increase linearly with speed. Doubling speed increases drag four-fold! So you are unwittingly giving an advantage to slower vehicles while penalizing speed. That’s backwards thinking.
Some interesting numbers in addition to the Bicycle numbers above- add an efficient motor to an ebike and the MPG goes way up: https://www.youtube.com/watch?v=0zJHMMYa01g
“I assume 4000 lbs per passenger, since that’s roughly the weight of a passenger vehicle.”
Why are you figuring the load of each passenger as a driver plus vehicle? Should be the average weight of a passenger plus luggage like all other examples used. Your comparison is grossly illogical.
For City transit the ideal solution is minibuses owned and operated by individual commuters who were already making the same trip by car but trying to pick up extra income by doing the same trip in a minibus. So from Brooklyn or Queens into Manhatten mini bus drivers would pick up commuters on the big avenues that aren;t near the subways and ferry them into the city. Virtually no labor cost because the guy is commuting into the city anyway. Little marginal energy or vehicle cost because he was driving in before (albeit in a smaller car). High fuel efficiency because only does the trip in the morning (and back out in the evening) so his van is always near full (no off peak travel). It’s actually a practical suped up version of carpooling. Thousands of middle class people commute intot the city by car. Bus unions would never allow it so they are a huge obstical to energy efficient city transport. Too bad…
Wouldn’t it be a parking nightmare especially in a place like NYC? Or are these mini busses small enough to fit into the same parking spaces as normal commuter vehicles? Wouldn’t it be better to feed people from non subway areas to nearest stations? I assume local busses already do that. Maybe the subway is already at max capacity. But if not why not.
It would be interesting to add life cycle energy costs. This could include energy costs to produce bike or car, averaged out over average distance traveled. Also, energy costs of extracting oil, refining, transporting and delivery and also the energy costs of producing and delivering food. I have seen estimates of 100 mpg for meat eating cyclists and 200 mpg for vegetarian cyclists when life cycle costs are analysed.
This is really misleading. You make a conversion between the calories burned by people walking, running, or riding a bike, and the calories in fuels like gas or diesel.
That neglects a HUGE issue, which is the energy required to produce a calorie worth of food.
It totally depends on which foods the person eats. For example, a vegetarian diet requires much less energy input (farming equipment, fertilizer, transport, etc.) to produce a calorie of food, vs. a fish-eater, vs. a meat-eater (by far, the worst).
This isn’t a small factor. Getting your energy from beef requires several times the amount of usable food energy in the beef, to bring it to market.
Depending on various factors, it takes from 6 to 50 times as much energy input to get a unit of beef energy output. Compare that to gas, which requires about 10% of the output energy to produce. Even biofuels are now at about a 1:5 energy ratio (1 unit energy input yields 5 units of output … the extra energy, of course, coming from the sun and converted by photosynthesis).
Growing animals, and feeding humans, to produce work, is hugely wasteful. Sorry, writers of “The Matrix”.
When you account for this (even if you account for similar production costs in making gas/diesel/electricity), you realize that the human body is really, really inefficient.
12 November 2012
Comparing the fuel economy of any bus to an Amtrak train is meaningless. How many busses drag diners, sleepers, roomy coaches and observation cars around with them? If there were a bus “Superliner” (a “90-wheeler”?), and if anybody ever let one out on the highway, then you’d have your “apples to apples”.
Busses are better compared to Light Rail Transit (LRT) or Modern Streetcars, whose interiors comprise mostly seats and maybe a rest room, and which at any rate are both missing from your table. Be it measured in “PMPG’s” or the Kilowatt-Hour equivalent, the fuel economy gap between busses and Urban Rail vehicles is really wide. Factor in factors (sorry) like right-of-way life, vehicle life, the “rubber” tire disposal problem, and the fact that streets and roads are themselves made out of petroleum products, and that gap becomes more like a chasm.
Your comments calling for greater ridership on Amtrak and for more little busses are right on the mark. As are your tables in general. I think.
Buses: At average passenger loads, buses achieve 3262 BTU per passenger-mile, or 38.3 pmpg. Per BTS data, buses average 6.1 diesel mpg, or 5.5 gas mpg. With a full load of roughly 60 passengers, a max pmpg of 330 is possible. The huge difference in average and max pmpg implies that buses are usually almost empty – perhaps smaller mini-buses should be used by more fleets.
Please convert this in KM and Fuel (liters).
What is the standard of fuel consumption rate for heavy duty coach buses (55 t0 70 passengers). Do have the industry standard rate which is established?
I in public passenger transport covering distances of 646 km on 250 ltrs of diesel and carry about 55 to 70 passengers at most.
I want to work out my fuel efficiency level not with standing the elements of driver behavior, regular service and the condition of the vehicle.
What would you advise/help.
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I think you’re over-inflating the shipping MPG versus trains. This is just a hunch, but railroads tend to be very labor-intensive versus just about anything, while an individual ship is going to usually have substantial scale advantages over the train.
I’m not going to say that the numbers are wrong, but I believe they’re distorted by non-fuel costs that pile up on the side of the railroads.
I’d be interested to see someone try and figure out the numbers needed for a cruise that was comparable in service levels to Amtrak…again, the ship has scale advantages that simply don’t apply on overland transportation in any form (you’d need somewhere close to 100 Viewliner sleepers to equal a single one of the larger cruise ships, to say nothing about dining cars and lounges).
Gray, not sure I get your comment – I have ships listed as having double or triple the MPG of trains – and this is consistent with the costs of shipping via the two methods, which means it’s in the right ballpark.
Unfortunately, people eat food, and in the US, each calorie of food eaten takes something like 7 to 10 calories of fossil fuel to produce, distribute etc. Sadly, this reduces the PMPG of biking, walking, and running by this same factor
Yeah, this is a MONSTROUS omission in this analysis. For people fueling themselves with meat, that particular food can easily take 50x the output energy to produce, as you have to grow grains and keep cows alive for months before you slaughter them.
Fossil fuels also require fossil fuels to produce, but not nearly as much. You get about 10 units of gas energy out right now for each one unit put in (although that ratio gets worse as time goes on, and we have to drill deeper, and use tar sand oil).
Biodiesel made from US soy, or ethanol made in Brazil from sugarcane, can yield about 5 units of energy for 1 unit input these days.
The human body is not an efficient machine.
n8r0n, there is no omission in the analysis. This is simply an mpg comparison. How you get the input energy into the vehicle, whether a human onfoot, or a vehicle, was left out of this calculation as that’s not typically how mpg numbers are measured – you don’t worry about whether you are getting $10/barrel Saudi oil with 100:1 EROEI or low EROEI oil from an ultra deepwater well when you buy gas, do you? A full lifecycle calculation of each vehicle and each potential fuel type was not attempted here.
The important point I made elsewhere in the comments also holds – most Americans consume excess calories on a daily basis that are simply tacked onto their waste lines (until they reach caloric balance at a heavier mass than they’d probably like). Now I realize that most Americans aren’t willing to walk/bike/run anywhere anyway, but if they were, it wouldn’t have to mean eating more food than they already do. Instead of feeding calories into a 250lb frame composed of 30-40% fat, they could be feeding the same calories into a sub-200 lb frame of 10% fat, with the excess energy going into their commute.
Love this data!
Wondering about the cost of food versus the cost of gas and electricity.
If a cyclists burns 32 cal/mile, a 10 mile commute would require 320 calories.
A bit more than in your average power bar.
Say you buy your power bars at Costco, they might cost a buck each.
That .1/mile or 10 miles for every dollar, expensive.
What value can we attribute to cost/calorie for food in general?
Greg,
Great comment. While a Powerbar may be realistic in terms of what a cyclist might want to eat, it’s not really a fair comparison since it’s a prepared food with a lot of the markup associated with that.
Perhaps at another extreme, 3oz of uncooked rice is around 330 calories, and at $2 a lb, that’s 20 cents to pay for the needed commute energy.
http://www.fatsecret.com/calories-nutrition/generic/rice-white-cooked-regular
But here’s the most important reason that I think this reasoning under-appreciates commuting on human power: most Americans eat too much to begin with, and have plenty of calories to spare. So in many cases you have to draw that down before the energy cost of bike commuting rises above zero. Me personally – I used to be more fit, but I could use the human commute these days!
This is totally wrong. People who exercise more will also eat more.
I used to work with a tiny little Chinese woman (100 lbs, maybe), who biked an hour each way to work. This little person, who probably would have consumed less than 2000 calories per day with a normal routine, was easting 6000 calories per day. And, she ate lots of meat and poultry, which is a terribly inefficient way to get your energy.
And, as you might expect, she was not overweight. Very fit.
Biking to work is great if your objective is to be fit. It’s terrible if you want to be energy efficient.
question: what would a tandem bike get?!
I’ve heard that scooters/mopeds get really high mpg, over 100 in many instances. with two people on one of these, it would rank pretty dang high.
I like your analysis.
The speeds you used for walking (3 mph) and biking (10 mph) would be easy for most people. However, I don’t know many people that routinely run at 6-minute pace (10 mph). I thought the value for a slower rate (say, 6 mph, or a 10-minute pace) would be a more useful metric.
I plugged in the calories/hour for various speeds from the website you linked to, and to my surprise the PMPG is fairly consistent for running speeds varying from 6 mph to 10 mph. (And if the numbers are to be believed, running at 8 or 9 mph is slightly less efficient than running at 6 or 10 mph!) For jogging/running at a 10-minute pace, we get a PMPG of 320. Interesting.
kgarlow,
You’re correct – when I looked into it, I found that running seemed to consume a pretty constant 100-odd calories per mile regardless of speed. This means the pmpg is about the same across the board. It’s been a while, and I can no longer remember why I picked 10mph for running – maybe it’s wishful thinking for a time when I used to run that fast! But since the PMPG for 8 or 10 minute miles is about the same, it doesn’t throw it off much.
It would be great if you could split out intercity buses from transit buses as they are massively different in terms of load, and to a lesser extent efficiency. I’m willing to bet that Greyhound does a lot better efficiency-wise than Amtrak.
John,
If you look at the max PMPG for trains and buses, you’ll see that a full bus gets 330PMPG, which is almost double a passenger train’s max.
Now we both know that Amtrak trains are often pretty empty, particularly outside the northeast, while Greyhound and other buses are often pretty full (witness the explosion of Chinatown buses in the Northeast).
So inter-city buses at 80% capacity are probably managing 250+ PMPG while Amtrak is in the mid double digits at best with its near-empty trains. You’re right, there’s no comparison.
One more note – most city buses would be better off replacing their fleet with rental car shuttle style super-sized vans. It’s so common to see empty city buses, and it’s rare to see one so packed it needs 40+ seats. Why not use 20 passenger vans that are smaller and more efficient?
Actually interestingly the AATA talks about this in their FAQ: http://www.aata.org/faq.asp (scroll down to ‘smaller buses’). I think there are regulations in place or something that require them to have the sort of buses that you’re used to seeing rather than vans… maybe an ADA thing?
Anyway I agree wholeheartedly with the principle of just using vans, and if it is a regulatory thing it probably needs to be rethought. On a related note, NYC is about to bring back dollar vans!
I’m not sure if your including the cost to plug in and recharge the hybrid. If not, it is not a valid comparison.
Bob,
The plugin hybrid numbers do indeed include the cost of electricity – a cost of 10 cents per kWh of electricity is typically built into these calculations.
How much electricity do you count as a gallon?
Kind of an ugly trackback, sorry. I reached your article through a reference on The Oil Drum.
I think you have done a lot of good work here, and thanks.
I don’t quite get the 4000 lb comparison, so I’ll suggest another method:
For freight carriers I’d like a chart per pound/kilo and for passenger carriers a chart per avg person. This would allow me to compare plane-light rail-bus-prius-motorcycle-bicycle-walking and ship-rail-truck-plane. Perhaps you’ve already done these calcs? I’ll poke around.
John, I believe others have done the calculation as you suggested – I wanted to get all of the metrics on one scale, so I was forced to use some metric for converting between freight and human transport, and I chose the average weight of an individual automobile.
Having said that, since I used a consistent conversion metric, you can compare ship-rail-truck-plane on my chart, and see that ships are most efficient, followed by rail. Planes and trucks are actually fairly close together – trucks suffer in these calculations since they often travel lightly loaded, whereas planes these days are typically packed to capacity (whether cargo or people).
This “logic” effectively penalizes 18- wheelers by a factor of about 20. You obviously did not figure the passenger load for any other vehicle as 4000 lbs per passenger. (Certainly not the bicycle. lol) So, you need to divide the average cargo load of an 18-wheeler by around 200lbs, not 4000lbs in order to get a sensible comparison. Sorry to be a jerk, but what else is there for an unemployed nuclear engineer to do for fun these days?
That’s a fabulous analysis. The first thing that occurs to me is to wonder what the ranking would look like if you adjusted it for average delivery time. We obviously burn a lot of fuel to ship people cross-country in an airplane, but few people have the available time to walk or bike. Riding a train or car would be in between.
This would make for interesting differentiation between, for example, typical US trains (60-70mph) and European and Asian (and the rare US) “bullet” trains (200+ mph as I recall). I suspect (without any data) that fuel economy is not much different between the two, but delivery time is different by a factor of more than two. It is possible that in some cases the reduced delivery time would be enough to increase ridership, thus moving further toward the max achievable PMPG.