The Ethanol Papers - Paperturn manuscript - Flipbook - Page 223
precisely the same directions, for the same length of time, and exactly the same
speed (not just close to the same speeds), you can't make an accurate comparison between the two roundtrips.
In addition, as the writer pointed out, there were different traveling speeds in
the outbound and inbound drive. While you can say "X will make up for Y" in a
general sense, you don't really know if X plus a wind speed of 10 MPH can be
directly offset by Y plus the same wind speed. And this doesn't even account
for how the vehicle burns gas at the different speeds. It's possible that if the
vehicle's optimum MPG efficiency is attained at 60 MPH, 65 MPH could produce
significantly different MPG results than 55 MPH, even though both speeds are
5 MPH different than the optimum. Over a protracted distance travelled even
the slightest difference can add up to an alarming difference, but unless that
distance is traveled on a regular basis by an individual then the difference could
be irrelevant in their consideration of which fuel to use.
In my estimation a more correct test would be to have two identical vehicles,
using different respective fuels, with equal payloads traveling alongside each
other for the entire distance - whatever the distance might be. Also, either vehicle would have to avoid any "drafting" assistance that might occur if either vehicle followed too closely another vehicle. On the other hand, a pure engine
bench test with equally optimized engines - one optimized for 100% alcohol and
one optimized for 100% unleaded gasoline - is probably the only way to do it.
In my understanding, any bench tests conducted of optimized engines have
shown that the MPG efficiency is equal.
I think the important point to learn from the Edmunds' test is that the results
were quite similar and that the writer did not report that the vehicle suffered any
damage to its engine due to using alcohol. As you may know, one of the pernicious "manufactured" complaints made against the use of alcohol in a "gasoline" engine is that alcohol will damage it.
One more point on the Edmunds' test: If you go to a filling station that sells e85,
you may notice a little sign that reads that the e85 may in fact only contain 70%
alcohol, not 85%. I don't know enough to be able to say if the difference in the
15% could produce better or worse results, but it seems likely that there would
be some difference. If the vehicle was adjusted to run as an e85 flex-fuel vehicle
but it was only being fed e70, then it is conceivable that the fuel economy would