Why "Gallons Per Mile" (or L/100 km) makes more sense

[MetroMPG]

Here's a quiz: In your Honda Insight you drive one leg of a trip, uphill and into a headwind, and get 50 mpg. On the way back you get 100 mpg. What's your round trip MPG?

[wagonman76]

I agree, thats something I was thinking about on the way home today. There are basically 2 good ways I can go to work. I usually go the way that is 25 miles and 50% highway, and gets me about 29 mpg. There is another way that is more like 75% highway and would get me more like 30 mpg, however it is 30 miles so the added distance outweighs the mpg gain. The in-laws live that way so I only go that way when Im stopping by there.

Also there are other things that sometimes outweigh fuel efficiency. I typically run my tires at like 30 psi. I could pump them up and pick up another mpg, but that makes the car get beat up a lot harder by these horrible Michigan roads, and ends up costing me more in repairs.

Originally Posted by Arminius

In addition, there is another twist in calculating FE. For example, my present average is about 41-42 mpg. I can easily get 46 mpg if I take another route to and from work. However, that particular route is long enough to cost me an extra 12 more cents a day in gas than the route with lower mpg, which is shorter. Therefore the FE of the engine and the FE of the route are in conflict.

My ego makes me want to take the higher mpg route so that I can brag about my efficiency. Logic and my conscience demand I take the more efficient route, which has lower mpg.

[dremd]

Originally Posted by MetroMPG

Here's a quiz: In your Honda Insight you drive one leg of a trip, uphill and into a headwind, and get 50 mpg. On the way back you get 100 mpg. What's your round trip MPG?

66.67MPG ? Or is my dyslexia showing?

[diesel_john]

BTU's per mile

[Cd]

I found this the other day in a magazine ad :

Hmmmm....

[Arminius]

Originally Posted by .Cd

I found this the other day in a magazine ad :

Wow, a used car at double the original price. Good luck with that!

[Arminius]

Originally Posted by MetroMPG

Here's a quiz: In your Honda Insight you drive one leg of a trip, uphill and into a headwind, and get 50 mpg. On the way back you get 100 mpg. What's your round trip MPG?

75 mpg. The wind and the hill info are not necessary for the computation.

[Bigs]

Originally Posted by Arminius

Wow, a used car at double the original price. Good luck with that!

Yep! LMAO!


Back on topic, I don't mind the MPG's... This is what the older folks like my parents still use. So I'm used to both ways!

[tasdrouille]

Originally Posted by Arminius

75 mpg. The wind and the hill info are not necessary for the computation.

You just proved the article is right. Suppose 50 miles. At 50 mpg you use 1 gal and at 100 mpg you use 0.5 gal. Total fuel for the 100 miles trip is 1.5 gal which turns out to be 66.6667 mpg.

I'm a Canadian, but an ambiguous one I guess. I measure long distances in km, but anything below 100 m will be in feet. I measure large volumes in liters, but anything below 1.15 liter will be in ounces. I'm consequent with weight though, tons and pounds all the time, but I guess I should be using the metric system...

Anyway, I really don't like L/100km. I don't know why, maybe because it does not vary much. A change from 7.5 to 6.5 L/100km doesn't sound like much to me. 31 mpg to 36 mpg speaks a lot more IMHO.

[Figjam74]

Well, I could see the benefit of L/100km for the 2 days my scanguage worked. Let's say you get 35 mpg. At idle, that drops to zero. In L/100km your normal 6.7 would suddenly jump to 9999... I find the latter far more alarming.