Originally Posted by
TownDrunk
Lean cruise currently requires premium (91 or 93 octane) fuel. It's possible we may make that work with regular gas again.
The alcohol sensor is only required if you want to burn any fuel, E85 or E10 or anything in-between. For example, you might normally fill with E85, but while traveling, it's not available. So you could use regular or premium until you can find an E85 station again. Otherwise, if tuned for E85 and you fill with regular, you'd get a check engine light (too rich) and poor mileage and could even ruin your catalytic converter.
Many people burn E85 because it's a LOT cheaper than premium (or less polluting, or made in America). Usually it'll save you money if more than 20% cheaper. For the Volt this is great because the Volt likes high octane fuel and E85 is usually around 97 octane while premium is 91, maybe 93 octane and regular gas is 87 octane. Since we tune for E85, you'll get better mileage with E85 than most FFV's because they're rarely optimized for E85. Although cheaper, you'll still have to fill more often since you'l get between 15 and 20% less miles per tank.