# Question about fuel consumption and airplanes **URL:** \ **Category:** Factual Questions\ **Created:** [December 18, 2014, 4:29pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581 "2014-12-18T16:29:10Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Robert163](https://avatars.discourse-cdn.com/v4/letter/r/4af34b/32.png) [@Robert163](https://boards.straightdope.com/u/Robert163)\ **Post date:** [December 18, 2014, 4:29pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/1 "2014-12-18T16:29:10Z")
We’ve all heard about how much fuel airplanes consume. My question is, if everybody (or group/family unit) on that plane each drove a car the same distance as the flight, would the combined fuel of the cars be more or less than that of the airplane? ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [December 18, 2014, 4:53pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/2 "2014-12-18T16:53:00Z")
[This article](http://www.slate.com/articles/business/the_juice/2014/07/driving_vs_flying_which_is_more_harmful_to_the_environment.html) discusses your exact question, and gives figures in energy per passenger-mile. The plane is more efficient today, though in the past driving was much more efficient. That’s because both the planes themselves are more efficient, as well as the airlines making their overall operations more efficient (more efficient flying, more people crammed in each plane, etc.) ---
**Author:** ![Robert163](https://avatars.discourse-cdn.com/v4/letter/r/4af34b/32.png) [@Robert163](https://boards.straightdope.com/u/Robert163)\ **Post date:** [December 18, 2014, 4:57pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/3 "2014-12-18T16:57:22Z")
> [@lazybratsche](#): > > [This article](http://www.slate.com/articles/business/the_juice/2014/07/driving_vs_flying_which_is_more_harmful_to_the_environment.html) discusses your exact question, and gives figures in energy per passenger-mile. The plane is more efficient today, though in the past driving was much more efficient. That’s because both the planes themselves are more efficient, as well as the airlines making their overall operations more efficient (more efficient flying, more people crammed in each plane, etc.) thank you ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 18, 2014, 5:28pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/4 "2014-12-18T17:28:56Z")
Please check me on this. Stipulating that airplanes don’t calculate fuel consumption in miles per gallon: A typical four-seat airplane with 150 or 160 horsepower gets about 14 mpg in cruise in still air. If you (can) fill all of the seats, that’s like 56 mpg right? Put another way, if I fly alone I’m paying for all of the fuel. With three passengers, each person is paying 25% of the fuel (stipulating here that there are rules for cost-sharing). So even though the airplane is actually getting 14 mpg, it’s as if each person is paying for a vehicle that gets 56 mpg if they were driving alone. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [December 18, 2014, 5:38pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/5 "2014-12-18T17:38:14Z")
I had the picture from the OP of four people either in a sedan or in a light general aviation airplane, kind of like what Johnny L.A. is referring to. In the case of general aviation it’s considerably tougher to get better efficiency in a plane than a car. The article, if you haven’t read it, is comparing airline efficiency versus auto. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [December 18, 2014, 6:04pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/6 "2014-12-18T18:04:27Z")
> [@Johnny\_L.A](#): > > Please check me on this. > > Stipulating that airplanes don’t calculate fuel consumption in miles per gallon: A typical four-seat airplane with 150 or 160 horsepower gets about 14 mpg in cruise in still air. If you (can) fill all of the seats, that’s like 56 mpg right? Put another way, if I fly alone I’m paying for all of the fuel. With three passengers, each person is paying 25% of the fuel (stipulating here that there are rules for cost-sharing). So even though the airplane is actually getting 14 mpg, it’s as if each person is paying for a vehicle that gets 56 mpg if they were driving alone. You could have a similar discussion about a Greyhound bus that gets 6 miles per gallon. If you fill 50 seats, then you’re achieving 300 passenger-miles per gallon. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [December 18, 2014, 6:11pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/7 "2014-12-18T18:11:17Z")
Here are fuel economy numbers for a lot of commercial planes, expressed on a per-passenger basis: > **[Fuel economy in aircraft](https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft)** > > The fuel economy in aircraft is the measure of the transport energy efficiency of aircraft. > Efficiency is increased with better aerodynamics and by reducing weight, and with improved engine BSFC and propulsive efficiency or TSFC. > Endurance and range can be maximized with the optimum airspeed, and economy is better at optimum altitudes, usually higher. An airline efficiency depends on its fleet fuel burn, seating density, air cargo and passenger load factor, while operational procedures like ma... If you’re willing to pack three or four people in a car with middling fuel economy, you can match the per-seat fuel economy of most of those planes. Of course the trip will take ten times as long. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 18, 2014, 6:20pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/8 "2014-12-18T18:20:33Z")
> [@Machine\_Elf](#): > > You could have a similar discussion about a Greyhound bus that gets 6 miles per gallon. If you fill 50 seats, then you’re achieving 300 passenger-miles per gallon. Ever ridden the dog? _shudder_ It’s worse than a commercial airliner. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [December 18, 2014, 7:02pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/9 "2014-12-18T19:02:14Z")
Another point is that aircraft fly pretty much point-to-point, which depending on the route can shave a significant amount versus the road mileage between two points. ---
**Author:** ![JerrySTL](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@JerrySTL](https://boards.straightdope.com/u/JerrySTL)\ **Post date:** [December 19, 2014, 3:18am UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/10 "2014-12-19T03:18:49Z")
There’s also the time value of money to consider. For example 12 hours in a car versus 4 hours on an aircraft. Of course you would need to factor in waiting at the gate and the friendly TSA people. Once you get much past a 12 hour drive, you’ll need to find sleeping arrangements such as a hotel which adds to the cost. Something else to factor is wear and tear on your car on longer drives. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [December 19, 2014, 3:56pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/11 "2014-12-19T15:56:53Z")
> [@JerrySTL](#): > > Something else to factor is wear and tear on your car on longer drives. FWIW, most of the engine wear happens in the few minutes after a cold-start; long trips in a car are only cause marginally more wear to the engine than short trips. That said, driving does wear on other things. And your insurance is higher the more miles you drive per year. And you have to do regular maintenance: brakes, oil, tires, etc. The general rule of thumb (and what the IRS currently allows for deduction purposes) is [56 cents per mile,](http://www.irs.gov/2014-Standard-Mileage-Rates-for-Business,-Medical-and-Moving-Announced) meaning this is a fairly typical value that accounts for depreciation, maintenance/repair, fuel, and insurance costs. This is true of short trips as well as long trips. So a 1200-mile drive might cost you $672 by car, but $300-$400 by air. And then as you noted, there is the time value of money: a 1200-mile drive might take 20 hours (assuming a 60 MPH average here, not considering an overnight stop), but the flight might only take 6 hours (3 hours gate to gate, plus 2 hours of hassle prior to departure and another hour of hassle after arrival) ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [December 19, 2014, 4:04pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/12 "2014-12-19T16:04:26Z")
> [@md2000](#): > > Another point is that aircraft fly pretty much point-to-point, which depending on the route can shave a significant amount versus the road mileage between two points. No they don’t. Airplanes fly airport-to-airport, or airport-to-hub-to-airport. Your actual starting point and destination may be hours away from the airports, and not in a straight line. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [December 19, 2014, 5:11pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/13 "2014-12-19T17:11:33Z")
> [@Machine\_Elf](#): > > If you’re willing to pack three or four people in a car with middling fuel economy, you can match the per-seat fuel economy of most of those planes. Yes. But the average load in a car (percentage of seats that are occupied) is probably a lot lower than the average for commercial aircraft. > [@](#): > > Of course the trip will take ten times as long. Depends. For trips of under, say, 300 miles I’d guess the door-to-door time in your car is typically lower than if you go by plane. Longer trips shift the balance, and by the time you’re flying across the country, the plane’s advantage is huge. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 19, 2014, 6:10pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/14 "2014-12-19T18:10:37Z")
> [@Xema](#): > > Depends. For trips of under, say, 300 miles I’d guess the door-to-door time in your car is typically lower than if you go by plane. Anecdote: Last month or a couple of months ago, traffic was so bad getting into Seattle that the traffic guy on the radio said you could turn back from Lynnwood, drive to Bellingham (61 miles), get on a Horizon Air flight out of BLI to SEA, and _still_ be to Seattle faster than if you continued driving the 16 miles from Lynnwood to Seattle. (And yes, I was stuck in it. I don’t remember if that was the time I turned around and went back to Birch Bay to work from home.) For trips up to 300 miles (maybe 400 miles), it’s often quicker to fly a Skyhawk or a Cherokee than to take a commercial flight – especially if you abide by the ‘get to the airport an hour early’ rule. Of course you’d have to have access to a Skyhawk or a Cherokee, and fill the seats to make it economical. ---
**Author:** ![sbunny8](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@sbunny8](https://boards.straightdope.com/u/sbunny8)\ **Post date:** [December 19, 2014, 6:52pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/15 "2014-12-19T18:52:24Z")
Going by the chart in that article in post #2 by Lazybratsche, if all those people got off the airplane and drove their cars instead they’d be burning more fuel. BUT that’s largely because the majority of them would be just one person alone in their car. If you are one of those lone travelers, then yes you’re burning less fuel on the airplane. But if you’re traveling with your spouse, the two of you would burn less fuel riding together in a car. Put it another way, the typical airplane might have 120 people on it, and 100 of them are flying alone so if the flight were canceled we’d see 108 cars leave the airport, burning MORE fuel. But if we imagine a plane with 60 couples on it, cancel that flight and only 60 cars leave the airport, which would burn LESS fuel. ---
**Author:** ![Doughbag](https://avatars.discourse-cdn.com/v4/letter/d/aeb1de/32.png) [@Doughbag](https://boards.straightdope.com/u/Doughbag)\ **Post date:** [December 19, 2014, 7:14pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/16 "2014-12-19T19:14:25Z")
> [@](#): > > In his piece describing why he took a 28-hour bus ride from Wisconsin to Atlanta, he noted that the amount of emissions associated with driving that distance in a Honda Civic (1,386 pounds of carbon dioxide) was roughly equal to the amount of emissions he would have caused in flying that distance (1,587). Note, of course, that the 2012 Honda Civic gets 39 miles per gallon on the highway, where most of that driving would take place—far above average. Sivak’s study points out that the average light-duty vehicle on the road in the U.S. gets about 21.5 miles per gallon. His study suggests that vehicles would have to get more than 33.8 miles per gallon in order to be less fuel-intensive than air travel. Many cars do more than 60 mile/gallon these days - at least in Europe. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [December 21, 2014, 4:00am UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/17 "2014-12-21T04:00:14Z")
> [@Machine\_Elf](#): > > You could have a similar discussion about a Greyhound bus that gets 6 miles per gallon. If you fill 50 seats, then you’re achieving 300 passenger-miles per gallon. Economy of scale is pretty universal. Its why they built huge ocean liners, wide-body airlines, VLCCs etc. > [@Doughbag](#): > > Many cars do more than 60 mile/gallon these days - at least in Europe. What cars are these?! 😕 ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [December 21, 2014, 9:26am UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/18 "2014-12-21T09:26:38Z")
> [@Hail\_Ants](#): > > Economy of scale is pretty universal. Its why they built huge ocean liners, wide-body airlines, VLCCs etc. Not quite with the airplanes. The 70 seater ATR-700 does better than a number of much larger aircraft, like 747… Of course the 747 replacements that are newer than the ATR-700 do better … The idea is that there are numerous trade offs at work, for example, range vs efficiency. ---
**Author:** ![Doughbag](https://avatars.discourse-cdn.com/v4/letter/d/aeb1de/32.png) [@Doughbag](https://boards.straightdope.com/u/Doughbag)\ **Post date:** [December 21, 2014, 1:39pm UTC](https://boards.straightdope.com/t/question-about-fuel-consumption-and-airplanes/707581/19 "2014-12-21T13:39:38Z")
> [@Hail\_Ants](#): > > Economy of scale is pretty universal. Its why they built huge ocean liners, wide-body airlines, VLCCs etc. > > What cars are these?! 😕 Many… here is a quick short list… for the most part all car brands offer models that can even go further than the 60mpg. [Volkswagen Golf](http://www.volkswagen.ie/content/medialib/vwd4/ie/pdf-downloads/product-guides/new-golf-product-guide/_jcr_content/renditions/rendition.download_attachment.file/golf_october-2014.pdf) [Hyundai i30](http://www.hyundai.ie/car/i30?gclid=CjwKEAiA_NmkBRCe3ubC1aWAtEcSJACxkkbqcWQwmM0SkJDmBal0yWwmzEl0axkq5g56LPq8j8NvahoCdIbw_wcB#specifications) Some Audi’s get there as well. The [Renault Megan](http://www.renault.ie/media/e-brochures/cars/atted8a78f9704c42029de2f7e886c3e628/New_Renault_Megane_Brochure.pdf) Even the cheap [Dacia Logan dci90](http://forms.renault.ie/Dacia-Logan-Brochure.pdf) gets there at 3.8L/100km. Then there’s the [Mitsubishi Outlander SUV](http://mitsubishi-motors.ie/car/outlander/) goes 52.31 mpg … never mind the[Outlander PHEV at 1.9L/100km](http://mitsubishi-motors.ie/wp-content/uploads/2014/10/Mitsubishi-Outlander-PHEV-Equipment.pdf) but that’s a Hybrid. While we currently enjoy exceptional low pricing of €1.30 for Diesel per liter - up until last month it was €1.50 per liter and Petrol was €1.75 per liter - the fuel economy of a car plays a major role in the buying decision. \* As reference: 1 US gal = 3.79 liter 60 miles = 96.56 km\*