You're going to need a bigger gas tank because your mpg is going to take a huge hit. Aside from any other programming, sealing, whatever, you might need to do, on our VXs a hit in mileage is not something to look forward to.
Whatever range you get out of a tank now in your VX, figure 70% of that on E85. E85 has 33% less energy per unit volume than pure gasoline.
http://www.epiphergy.com/uploads/E85...ound_2_web.pdf
http://www.edmunds.com/fuel-economy/...ison-test.html
Plus the fact that until all E85 is made from non-food-grade sources (such as "switchgrass") it hurts the economy when farmers grow corn for fuel instead of food. Right now it is mostly made from corn, with some food crop waste (rice husks, corn husks) being used. No large volume non-food sources are economically up to speed yet.
And if you're planning on making and storing your own E85, be aware of the emissions the stuff has while in storage, and how to store it safely. I am a Mechanical Engineer in the oil and gas engineering business (I know - the bad guys, I'm sorry), and we had one client that was switching a fleet vehicle tank farm from gasoline to E85, and had to spend many thousands of dollars modifying the tanks to safely store the E85.
Just playing Devil's Advocate here.
