Quote:
Originally Posted by fourtailpipes
it's funny you bring this up... my old college roomate is doing his thesis for a PhD in materials science engineering about exactly this. so far, his research has shown that in more modern engines, the rpm and speed ranges for optimal fuel economy tend to be quite a bit higher, mostly due to recent improvements in thermal efficiency (and aerodynamics). his data isn't all compiled yet, but he's telling me that most of his data points toward nearly 70mph being the best for his targeted data set (cars manufactured after 1/1/2000). obviously this is a data set with MANY extraneous points, so at best you can conclude on a sweet spot, not a rule.
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That's good to know! I know vehicle aerodynamics affected this "sweet spot" but didn't realize thermal efficiency also played a role. I assume that the "55" rule was made back during the 70's oil crisis when cars weren't exactly the pinnacle of aerodynamic design. I guess we'll have to play around with our speeds and see at what speed and higher the steepest "drop-off" for efficiency is
