Fuel Economy by Speed

A while back I wrote Does Driving Slower Save Gas?. My dissertation prevented a more complete analysis, which is presented here. The main result of the previous post was that according to the Federal Government, driving at a steady speed of 55 mph maximizes fuel economy. I and my readers found this rather hard to believe, so I emailed the relevant authorities, who quickly responded that the basic chart is a distillation of data presented in tables 4.24-7, in Chapter 4 of the Transporation Energy Data Book. From there, we find that three studies were performed measuring fuel economy at steady speeds-- in 1973, 1984, and 1997. Each of these came back with different results, basically because they were using wildly different automobiles.

Let me say that it appears the tests of these vehicles are impeccable. Great care was taken to standardize the conditions and get real operating data on these models. That being said, it is very hard for me to justify using data from one 1993 Subaru Leagacy and one 1997 Toyota Celica as a basis for a generic 2005-6 model car.

The 73 study used


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This page contains a single entry by Kevin published on June 22, 2005 4:30 PM.

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