10 to 12 mpg improvement is the same as 30 to 60 mpg

[jamesqf]

Originally Posted by tortoise

Again, any "debate" is only in your mind. The only point of the OP was that the biggest gain for the total population of vehicles is to improve the very low end MPG.

But in fact it is not the way to get the biggest gain, unless of course you have some sort of device, like those found in the unicorn corral, that magically improves fuel economy at little or no cost. In the real world,most people aren't willing to spend lots of time and/or money ecomodding their current 10-mpg vehicles, or significantly change their driving habits, so the only way you're going to improve fuel economy is to get them to change vehicles. When they are getting that new vehicle, a fraction can be persuaded to go for the 60 mpg alternative.

[briank]

As the OP contributor, what prompted me to analyze the mpg differences, is that I'm looking to change over to a hybrid from my current automatic 2008 Scion xB where I really average 30 mpg overall using coasting to stops, maximizing time in torque lock up. So I was doing a Total Cost of Ownership (TCO) analysis where I was examining used pre-2010 Prius vs new Prius C. From the analysis it looks like a lot of the lower cost of ownership comes from the slower depreciation per year of a used Prius, as much as it comes from the lower fuel costs itself. The Prius C while having slightly better city fuel consumption, this factor is so small in the overall costs, that other costs far outweigh it (first year depreciation of new car, much higher IL % sales tax on new cars). So my plan is to switch to a 2007-2009 range Prius and possibly achieve 60 mpg where I better implement hyper-miling techniques. Hence how the 30 to 60 mpg came about.

The slower depreciation of a 3 or 4 year old Prius along with high mpg means I think I will hit the sweet spot with TCO as I won't have finance interest, avoid collision insurance costs, do DIY repairs, brakes myself. I may lose somewhat if gas goes below $3/gal, but is that really losing, yeah the Prius might depreciate faster but gas then costs less and the economy as a whole benefits. Sorry for going off topic a bit.

[briank]

The Chevy Suburban owner will be rewarded with more $ savings for minimal effort compared to a Prius owner. That is a 1 to 2 mpg improvement with a Suburban is often more $ (gas) saved than 5 mpg or even 10 mpg improvement in a Prius. A Suburban owner may give up their effort thinking a 1 mpg is not worth it. A Prius owner may delight in a 5 to 10 mpg improvement where the opposite is the case when one looks at the $ saving for the effort.

Reducing brake use on a Suburban could give large fuel saving, that is the amount of stopping energy absorbed by the brakes, is the amount of extra accelerating energy that one would otherwise not need if they were at a constant speed for the same distance covered. That braking energy loss is why that city mpg figure is often half the highway mpg figure, even though your average speed is slower. Or to put it more bluntly throughout their life, the brake pads in a Suburban will consume upwards of a 1,000 gallons of fuel, depending on the amount of stop and go city driving, by turning your momentum into useless heat. Multiply that by the number of times you replace your brake pads.

[Frank Lee]

Interesting way to think of brake pads... My '94 F150 is still wearing the factory pads and shoes! I must not be turning disproportionately huge amounts of gasoline into brake dust on that one.