Whats a bigger jump 10>20 or 25>50mpg??

[mikeh501]

I'm not the brightest math geek on the planet, but i'm sure i'm not alone in thinking MPG is linear when it really isnt

"From the article: “There is a math illusion here,” said Richard Larrick, a management professor at Duke University, whose research appears in the journal Science.

Larrick said most people think improvements in miles per gallon are all the same, where a 5 gallon per mile improvement would yield the same gas savings in a car that gets 10 miles per gallon or 20 miles per gallon. (One mile equals 1.61 kilometers, and one U.S. gallon equals 3.79 liters.)

“The reality that few people appreciate is that improving fuel efficiency from 10 to 20 miles per gallon is actually a more significant savings than improving from 25 to 50 miles per gallon for the same distance of driving,” Larrick said."

http://www.mpgillusion.blogspot.com/

 

[Hate]

MPG surely is linear?

its miles / gallons of fuel used, simple.

say, you got 10mpg on 10 gallons, thats 100 miles
20mpg on 10 gallons, thats 200 miles
25mpg on 10 gallons, thats 250 miles
50mpg on 10 gallons, thats 500 miles

thus 10-20 gives you 100 more miles, and 25-50 gives you 250 miles.

So completely linear, or am I missing something completely obvious?

EDIT:

Yes I was being completely daft, using the same 100 mile distance...
10mpg = 10 gallons
20mpg = 5 gallons
25mpg = 4 gallons
50mpg = 2 gallons

 

[The Edge]

I've come to the same conclusion as he has over the past few weeks.

My old ZX diesel used to do 50mpg on a run, anywhere between 40 and 45 on a run towing, about 35 round town probably 32 towing and about 28 to 30 in heavy traffic.

My 2.0l petrol volvo 850 will do 35-38 on a long run, 32 towing about 25 to 28 round town and i dread to think what it does in heavy traffic!

They cost about the same to fill up (56litres diesel vs 70 litres petrol) and the volvo does slightly less to a tankfull.

The only differance with the Volvo is that it has a computer and tells me roughly what it's doing with the result at first that i thought "OMG!!" and drove it like a granddad. I've given up with that now and noticed - guess what - no differance.

The point is that i've gone from probably the most economical car that it's practical for me to own to one of the least economical cars that it's practical for me to own (Tool rather than toy tbh) and it's costing me only marginally more in fuel. Maybe £15 a month.

I think rather than thinking of it as linear once you get into the realms of sensible fuel consumption you need a very large saving to notice the differance. If you drive your car for a variety of purposes you're even less likely to see a differance because differant cars are better at differant things. My mum's 106 will beat the Volvo hands down round town, but for towing or motorway work the volvo will be better.

 

[mikeh501]

MPG surely is linear?

its miles / gallons of fuel used, simple.

say, you got 10mpg on 10 gallons, thats 100 miles
20mpg on 10 gallons, thats 200 miles
25mpg on 10 gallons, thats 250 miles
50mpg on 10 gallons, thats 500 miles

thus 10-20 gives you 100 more miles, and 25-50 gives you 250 miles.

So completely linear, or am I missing something completely obvious?

Well, I guess linear was a poor choice of words. I think it is linear for a given MPG, but what I had trouble with is that adding 5mpg to your average makes a bigger difference if your doing 10mpg than if your car already does 20mpg. I guess it makes sense, seems counterintuitive when comparing cars.

So I need to avoid the 5.0l V8 which does 10mpg, but the difference between the 2.0d (40mpg) and 3.0d (37mpg) Beemer is going to be miniscule! ....... except the miles per smile, which is likely to be large

 

[Hate]

Check my edit, its not linear if you're travelling the same distance

 

[mikeh501]

Check my edit, its not linear if you're travelling the same distance

Ill go back to my previous post, i'm no math geek