[Nerys]

So your normal highway is 23. the new 21mpg is your E10 highway. 17.5 is your E85 recorded.

$2.01 for E85 and $2.35 for E10 (this is not a valid comparison mind you since you were NOT geographically in the same place the only way to make this valid is for you to tell me what E10 cost around where you got the E85 for $2.01

For example I can not fairly compare NJ and PA gas because gas is a lot CHEAPER in NJ than it is in PA for the exact same gas only 6 miles apart from each other over the burlington bristol bridge about 30 cents difference.

On E10 you get 20.5 (I split the difference between 20 and 21)

On E10 your cost is 11.46 cents per mile 11.19 cents per mile if you get 21mpg
On E85 your cost is 11.48 cents per mile

You save nothing. its break even at 20.5 mpg you lose half a cent a mile at 21mpg but had to drive 100 miles to get it :-) and probably did some harm to your fuel system in the process (but just a tank or 2 on a relatively modern vehicle probably won't kill it)

Its interesting that you only lost 23.91% of your fuel economy on E85 compared to your normal 23mpg on E0 - mathematically thats not possible I would be curious as to whats going on inside your engine OR maybe you did not get E85 maybe it was lower E like E60 which would give you about what you got. (E85 means "upto" 85% ethanol it can be lower just like E10 means "upto" 10% ethanol wawa gives me 6-8% which is why I go their :-) Its also possible the E10 already in your tank mixed with the added E85 to average it out at about E60 (which would get you about the 24% loss the numbers show) but you say your second tank was ALSO E85 and yet got the same 17.5mpg. Very strange indeed.

Either way I am curious how you came up with the figures you did. all of mine say you lose on E85 no matter what MPG figures I use for your vehicle.

BTW your break even mpg using 2.01 for E85 and 2.35 for E10 is 17.54 mpg and this still ignored geographical price differences. I can take advantage of the cheaper NJ gas because "I WORK" in NJ so I always pass the cheaper NJ gas. it would not be worth going to NJ for gas if I did not work their because I would have to pay the $2 bridge toll which would each up the cost savings of the 30cents a gallon cheaper gas plus the gas to DRIVE their and get it.

Lets not forget about the indirect costs of using corn for car fuel such as arable land and food prices and subsidies that are paid back via increased taxation etc..