Switching back and forth do you see about a 20% reduction in mileage? My owners manual says 15% so I'm guessing closer to 20.
I dont know how the newer models are but some of the earlier models it was closer to 35-40% reduction in mileage. I looked at using it for a while when things first started coming out with it. But for it to pencil out it needed to be nearly half the price of regular.
I am guessing things have gotten better in recent years with flex vehicles but I still wonder if the price difference is really making up much of a difference when you figure the reduced mileage. Even if it was only a 20% reduction in mileage, at current prices the cost of E85 would need to be at least $1 less just to break even.
So at more than $1 reduction in price for E85 at $4.50+ per for regular/E15, assuming you are seeing around that 20% or less reduction in mileage you may see some benefit. But how much it pencils out to really depends on just how much savings/mileage reduction and the amount of miles you drive.
Just not sure it is worth it, although it may be getting to the point there is some benefit, in past years there just was not enough savings to offset the loss of mileage.
Im curious if someone has real world experience the actual mileage difference in a newer model car, Highway vs City/combined. It would be interesting to know what the current break even point is.