[MrRuss]

I've been running occasional tanks of E (generally measures ~ E50) over the last 2 years in my DD, around 100 miles a week, all city street driving, no highway. My MPGs are 18-19 with 91 (no 93 in AZ) and 16-17 with E.

Only one station near me with E and filled it last week at $2.99/gal vs. $3.70/gal for 91.

Generally using 91 was more of a convenience factor, couple stations right on my route home from work. Going exclusively E with these gas prices. Few miles out of the way is worth it.

[weemus]

I ran E on my old car. Easy power gain esp if boosted. Like running race gas all day every day. Biggest cons are:
1. Availability depending on where you live. I.E. it can be like a electric car where you have to plan trips around stations or you will need to switch maps back to 93 when you can't find E.
2. As someone said 33% or so worse fuel economy. Personally I think that is a non issue as you get more power for fuel but the big negative is the miles per tank shrinks 33%. Read #1. If you tank is now essentially 33% smaller and availability sucks it makes for a big annoyance. I used to have to carry E85 in fuel jugs to some events in Cali outside the Bay because there weren't pumps up north just so i could get home...

Otherwise its awesome.

[MrRuss]

On our cars with a flex fuel kit and tune you can run either or and any mix of the two with no need to switch maps.

Can't say my observation is the same for others but I only lost about 12% MPG from 91 to E, my savings are 19%. Include the power gains and that is more than a wash.
SPG is priceless

[Brudda*Termite]

I got a hold of a big time batch of E last week, I was datalogging yesterday and it was reading 74-75% throughout. I thought it might be high, the MPGs are garbage with this batch!