When the national 55 mph speed limit was lifted in the mid-1990s, I went from 55 to 65 mph, so as not to impede traffic - still driving the limit in the rightmost of 3 lanes.
My commute to work decreased by 90 seconds as a result of the increased speed.
My gas mileage dropped from 36 to 33 mpg. To me, the increased speed wasn't worth it. A crash at 65 mph has 40% more energy behind it than a crash at 55 mph.