Posted by Matt
Did everyone else already know that our government was providing a fuel economy website? News to me! There is a great section on gas mileage tips that includes the usual sensible driving recommendations, but also had the answer to a question that I've long wondered about: "If driving fast decreases fuel economy, does your fuel economy continuously go up the slower you drive?" The graph (and article) says no, there is an optimal speed for fuel economy that varies by vehicle.
I'm going to guess that this graph shows the maximum fuel economy that can be achieved at each speed. In other words, if you accelerate to 20 mph and then maintain that speed (on level ground?), the best mileage that you can get for the subject vehicle is around 25 mpg. I assume that your fuel economy WHILE accelerating to 20 mph will not necessarily match the graph, especially if you've got the pedal on the floor!
I guess the mpg drop off at the slower speeds doesn't really matter because you rarely get the chance to cruise below 30 mph anyway, so the more important points for frugalizers are to keep the top speed down and go easy on the pedal at all speeds. But you knew that already, right?
By the way, if anybody has access to a graph like this for late-model Subarus, let me know! The few graphs that I could find were posted by Prius owners and their curves are very different.
This blog contains some simple tips and advice from two regular guys. We're not accountants, financial advisors, or brokers, so follow, ignore, or discuss our ideas as you see fit.