Quote:
Originally Posted by vnx205
Does improving your fuel consumption from 14 mpg to 15 mpg save you as much money as improving from 28 mpg to 29 mpg?
Even though both are a 1 mpg improvement, the answer is No.
Would it be the same if you improved from 28 mpg to 30 mpg? No.
What improvement on 28 mpg would be needed to save the same amount of money?
The answer is 32.3 mpg.
In other words if you are getting 28 mpg, you need to get an extra 4.2 mpg to save as much money as someone on 14 mpg getting just 1 extra mile per gallon.
(10.7 L/100km to 8.7 L/100km versus 20.1 L/100km to 18.8 L/100km) (Numbers rounded to 2 decimal places to try to avoid making this look like a complicated issue)
Because mpg numbers are so big,the benefits of improvements for economical vehicles are exaggerated. The same problem applies to a lesser extent to km/L The more economical the vehicle, the greater the apparent benefit.
The mpg figures for a thirsty vehicle are quite small, so worthwhile savings are made to look insignificant.
If you work with L/100km, the problem disappears. An improvement of 1 litre/100km saves exactly the same amomut of money regardless of whether you are driving a Kenworth or a Prius.
Doesn't that make L/100km look more logical and less misleading than mpg or km/L?
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It is not a problem - you can simply put the argument the other way - the number you get simply depends on which way up you put the fraction - to use your argument, the same amount of money is far less significant to the Kenworth driver than the Prius driver. And there is no reason to use litres/100km instead of litres/km. Neither way of putting it is misleading to anyone with elementary numeracy, and the change from distance/fuel quantity to fuel quantity/100*distance was an unnecessary change that is used nowhere outside Australia as far as I am aware, so your view of what is more logical and less misleading is not shared by the vast majority of motorists worldwide both today and for the last hundred plus years. But as I said, it doesn't make a significant difference which method you use, the most important is to use what you are familiar with.
John