FACT: most, if not all flex-fueled vehicles built after
2005 no longer use a flex-fuel sensor unit
FACT: Vishnu's system is the only dummy-proof system
FACT: It's not hard to measure ethanol content of gasoline
FACT: It's not hard to figure out how to run at least 30% ethanol content to clean up ignition timing up to stock timing curves.
FACT: all tunes now have some form of ignition control (whether optional or standard) to advance and retard timing.
FACT: COBB, BMS, VISHNU all have some form of E85 maps. If you're in doubt of running E85, just do it
I've been running e50-e60 since January of this year and I can't go back to running 93 octane, It's addicting!
Take it for what it's worth, I can name a large number of vehicle's that use Lambda feedback to calculate the amount of ethanol content.