The Ethanol Papers - Paperturn manuscript - Flipbook - Page 274
condensation or other causes. The ethanol's hygroscopic characteristics allow
the engine to fire and then expel the moisture in the exhaust.
You'd think that a certified auto mechanic would know the difference. Unfortunately, from experience in arguing the issue, I can tell you that there are far too
many "certified mechanics" who should be labeled certifiably nuts, not certified
mechanics.
Regarding your question "Does ethanol affect gas mileage negatively," let me
break the question down. First, I'm sure that when you write "gas" you are
meaning liquid gasoline, and not air-like fluid gas such as natural gas or propane, right?
Okay, so the question should really be: Does the presence of ethanol in a gasoline-optimized internal combustion engine negatively affect the output (mileage) of that engine? The answer is yes, of course, it does. The reason it does
is that the gasoline-optimized engine is designed to run on the characteristics
of gasoline. If the same engine was optimized to run on ethanol then ethanol
would produce comparable or better output (mileage) results than gasoline in a
gasoline-optimized engine. The issue is optimization, not energy content or
BTU rating.
This can also be proven by trying to use diesel fuel in a gasoline-optimized
engine. Even though diesel has more "energy content" than gasoline (higher
BTU rating), if you filled your gasoline vehicle tank with diesel you would not get
more MPG, in fact you would get no MPG. This is because the gasoline-optimized engine is not optimized to run on diesel fuel. Similar to the ethanol-optimized engine scenario, a comparably sized diesel-optimized engine running on
diesel fuel will get better MPG than the gasoline-optimized engine running on
gasoline.
Now, the question is, if ethanol or an ethanol-gasoline blend negatively affects
the MPG of a gasoline-powered vehicle why would anyone use it?
The answer has three parts:
1. The lower cost of ethanol usually makes up for the loss of MPG in a gasoline-powered vehicle. If you were to use E85 in a vehicle and get 15%
fewer miles, but the E85 saves you 20% of the cost of ethanol-free gasoline, then you gain 5%. So, the use of ethanol doesn't negatively affect
your vehicle's MPG, it would have a positive effect.
