I will be the first to admit that mine is not a scientific study, but thought it might be of interest. I now have driven 40,000 miles, having kept track of all gas purchases. During the first 35,000 miles, while I tried to drive for good gas mileage, I typically drove at 65mph when conditions allowed. I had a lifetime average during that period of 52.389mpg. Then, during the last 5,000 miles, I kept my freeway speeds down around 55-57mph most of the time, and my average for that period alone is 56.86. (Total lifetime average is up to 52.91). I live in So. California, so I have the benefit of warmer temperatures, and I use the a/c, defrost, heat etc. sparingly. Most of the time the computer shows a slight difference in mileage on individual tanks, but I figure over the long haul my record keeping is pretty accurate.
By the way, I keep to the far right lane unless I need to pass a slower vehicle when I am driving at the lower speeds. That doesn't avoid entirely the ire of some motorists, most notably those in gas guzzling suv's and pickup trucks. But then, that's no surprise, is it? I have also been passed by many a Prius! Hey, folks, I bought mine for economy of operation, and if slowing down a little can produce these kinds of results, I'm willing!
By the way, I keep to the far right lane unless I need to pass a slower vehicle when I am driving at the lower speeds. That doesn't avoid entirely the ire of some motorists, most notably those in gas guzzling suv's and pickup trucks. But then, that's no surprise, is it? I have also been passed by many a Prius! Hey, folks, I bought mine for economy of operation, and if slowing down a little can produce these kinds of results, I'm willing!
