My 2 cents:

The $.45 per gallon ethanol tax incentive, aka: taxpayer funded subsidy, is due to expire at the end of the year unless Congress intervenes. Let's see whether ethanol can stand on it's own so-called merits.

My  recollection from data a couple years ago Brazilian use of ethanol accounts for only +/- 15 % of total BTUs generated all sectors transportation, industry, power generation, etc. Force of government needed to get to there? I don't have current data in front of me.

Up here in the northern Minnesota, E-85 is watered down with gasoline to E-75 so engines will light off when it gets cold during winter, lows being normally 25-35 below 0 degrees Fahrenheit usually January and February, colder occasionally. I personally know of absolutely no one owning a so-called "Flex Fuel" vehicle burning E-85/75. Loss of efficiency makes for higher cost per mile operation. Only reason for purchase tax advantage?

A variable compression motor to take advantage of ethanol's characteristics would be great but no one offers one to my knowledge. SAAB has a version some years back as I recall but not a dual fuel motor.

Another 2 cents:  LPG vaporizes poorly low temperatures. Just ask me Thanksgiving Day as I was trying to light off the barbecue to cook a turkey with thermometer bouncing off of zero Fahrenheit. Same goes for trying to start a LPG fueled vehicle. Fine for fleet operations, not for personal vehicle.

Re: AC diesels. Cirrus Design plans to offer a diesel power plant option as reported in the local Duluth, Mn newspaper. Haven't seen specifics.

Al Koivisto