Quote:
Originally Posted by ocnorb
Just a comment on Volt gas only mpg. Because I live at high altitude (5000 ft) I decided to try some ethanol free 88 octane gasoline. On longer trips my previous best was 42mpg (gas only).
In November and early December we took the same trip to the in-laws (Thanksgiving and Christmas parties) running the "Clear88 " and it got 46.5mpg each trip. Far and away the best mpg the car has gotten.
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Ethanol only makes sense in turbo cars; or when driving in excessive heat.
High elevation also robs some power off the engine, but unless its also hot there, I wouldn't use Ethanol gasoline.
Ethanol somewhat gives a leaner burn, increasing HP and torque minimally.
It also lubricates the top of the cylinders, which gives it higher torque.
On hot days, or with turbos under load, it delays pinging or knocking, due to it's higher octane content.
Nearly All these benefits don't apply if you're living in cold areas with a Naturally aspirated engine, and have a tuned car. Ethanol HP gain due to burning leaner, usually works a bit better on cars that from the factory run too rich.
But for normal cars, they will actually lose MPG, not only from the lower energy density of ethanol, but also due to the slower combustion of higher octane fuel. And unless the engine advances this slow burning fuel, it's going to result in lower MPG, lower performance, and lower efficiency overall.