Yes, on a stock for stock car, e-85 is not worth the $$ unless you want to lessen your usage on fossel fuel.
As for flex-fuel vehicles, they did used to run a fuel sensor, but now mostly use the o2 and knock sensor to tune. The miles per cost was about the same also, but they did make slight power increse with the E-85, like a tenth less in 0-60.
Ethanol is not a nearly as bad for the fuel system as methanol.
E-85 does make less BTU's then Gas, but since you use more of E-85 it does make more power.
Yes E-85 is an awesome 100 pump or ever 110 leaded replacement. I was paying over $5 per gal for 100 pump, but now $2.65 for E-85.
If you use a wideband, you tune the engine just as if you were tuning with gas. You use the same numbers. Say 14.7:1 for idle and 11:1 for WOT. It shows those numbers because the wideband display is programmed to show the gas ratio's. I hope that makes sense.
If you build a motor for E-85 a gas motor can't touch it, for power and fuel economy. That is why the flex-fuel cars don't really show any difference, not if they took a premium fuel car and made it flex fuel, it would be way better on E-85. E-85 likes timing and compression. I don't has a 3000gt, but my 4 cyl has 10.5:1 comp and will run 20 psi easily.
I'll have to find the article where they converted a VW diesel jetta to run E-85 and it got awesome power and mileage.
No matter what, street driven or raced, you will need more fuel and have to upgrade the fuel system. But on a stock car, I would say don't do it, it is not available everywhere, and harder to find than diesel at times. Then when you want to put gas back in you'll have to change it back.
Also it is Federally illegal to convert a car to run E-85, but so is removing you cat
