# 54.5 mpg's by 2025...

**URL:** <https://forums.speedlife.net/t/54-5-mpgs-by-2025/259691>\
**Category:** Shift518 Automotive\
**Created:** [July 29, 2011, 3:53pm UTC](https://forums.speedlife.net/t/54-5-mpgs-by-2025/259691 "2011-07-29T15:53:04Z")\
**Posts on this page:** 1\
**Showing post:** 39

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**Author:** ![Cossey](https://avatars.discourse-cdn.com/v4/letter/c/3ec8ea/32.png) [@Cossey](https://forums.speedlife.net/u/Cossey)\
**Post date:** [August 1, 2011, 7:38pm UTC](https://forums.speedlife.net/t/54-5-mpgs-by-2025/259691/39 "2011-08-01T19:38:53Z")

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> [@OMFG it's BEAUTIFUL out!](https://forums.speedlife.net/t/omfg-its-beautiful-out/44337/49):
>
> Hey Obama haters…
> 
> I believe at least the last 6 presidents promised to reduce our dependence on foreign oil and with the record high gas prices the last two wanted to remove dependence on all oil.
> 
> Will it work? Probably not, it’s all politics and correct me if I’m wrong but the republican house had to approve this.
> 
> People that hate one party but not the other irk me. Either hate all govt or just stop caring as it wont change and it’s still the best around.
> 
> As far as performance, those manufacturers will likely have to buy their way out of the rule or introduce other models to improve their avg brand MPG just as they had to do by 2015.
> 
> Porsche has a 15 mpg model? Introduce 100mpg equivalent electric track beast. Could work.

The thing that sucks is say a company makes two cars, one that gets 20mpg and one that gets 100mpg, while the average for the company is 60mpg, that is not the same as the CAFE required average.

CAFE uses the “harmonic” mean, not the simple arithmetic mean.  
The harmonic mean is measured:

X / (1/Y1 +1/Y2) = Z

X = Number of cars in fleet (2 in my example)  
Y = MPG of a car, continuing for each vehicle in the fleet (Y1 = 20, Y2 = 100)  
Z = CAFE measured average MPG across the fleet.

So by my calculations, CAFE would measure it as 33.33mpg across the fleet, but using the math we learned through school, it is 60mpg. Pretty fucked up IMO.

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