Scotty,
Is it wise to use GPM (Gallons per Mile) to compare fuel economy or the trusty old MPG? Somebody once told me that GPM is better to compare esp. low-fuel economy vehicles like SUVs or trucks as even a small difference shows up better (e.g. a vehicle that gets 16.7MPG is using 6 gallons every 100 miles, vs. another that gets, say, 25MPG is only using 4 gallons per that distance, etc.). It looks like a diminishing returns proposition once you hit Prius like numbers, which may be why Toyota doesn't seem to be putting too much effort into improving economy which has hovered around 50MPG for more than 15 years. Any thoughts?
Thanks!
Sam
It does not matter. Use whatever you want.
The difference is what data you want to monitor:
- fuel consuption over distance (GPM, l/100km etc.)
- distance driven with an amount of fuel (MPG)
@g-t
Nope, it makes a Yuge difference, esp. for vehicles that get poor fuel economy:
https://today.duke.edu/2008/06/GPMFuqua.html
Only difference is what data you want to monitor as written above.
It's up to you what you want to use. You can calculate wanted data (distance driven, used fuel) either if you use MPG or GPM.
Vehicles with poor fuel economy use more fuel per certain distance than those with good fuel economy. This means they can get shorter distance per certain amount of fuel.
@g-t
It's a question of diminishing returns. If you go from a vehicle that gets 10MPG to 20MPG that's a YUGE difference (that shows up very well when you use GPM--or liters/kilometer for 95%+ of humankind). When you go from 30MPG to 40MPG that is a minor difference, and in fact the higher up you go in fuel economy the more ridiculous it become to chase better numbers. This is one reason why Prius of 2021 basically gets the same fuel economy as a Prius of 2004. Improving Prius' fuel economy from 50 MPG to 60 MPG would only give minimal savings and this becomes quite clear when you use the GPM formulation. You might want to check out the Duke University professors' views at the link above.
I agree with your statements. It's easier to improve fuel economy from 10 MPG (0.1 GPM) to 20 MPG (0.05 GPM) than from 40 MPG (0.025 GPM) to 50 MPG (0.02 GPM).
@g-t
For anyone who doesn't find the idea of using basic Math when making major decisions in life (e.g. buying a car) an absurd notion, here are 2 links, one from a major news organization and another from a major research University:
https://scitech.blogs.cnn.com/2008/06/26/gallons-per-mile
https://www.fuqua.duke.edu/duke-fuqua-insights/larrick-gallons-mile
Sounds like an argument for the sake of arguing ? Is there a more productive way to spend time ???
@oldrangernut
Agreed
@oldrangernut
Arguing? I don't see it that way.
Don't overthink it. MPG is the standard that most everyone uses, so I would go with that. People like to use other measurements to make themselves feel better about owning a dually and getting 5 MPG.
@mod_man
Don't overthink it, but don't be thoughtless either 🙂 Check the Duke University professors linked above. Here is a sample quote:
The reality that few people appreciate is that improving fuel efficiency from 10 to 20 mpg is actually a more significant savings than improving from 25 to 50 mpg for the same distance of driving.
@mod_man
Maybe it's standard in U.S. In Europe we use l/100km. You can calculate wanted data from whatever you use.
Liters per kilometer like the rest of the world? 😀
Tomato to-mah-to
@mountainmanjoe
You seem to be a fan of the Dan Quayle school of spelling 🙂
https://www.youtube.com/watch?v=Wdqbi66oNuI