The average United States driver travels 29 miles per day and is driving a total of 55 minutes per day. (This is an average vehicle speed of 32 mph.) US Department of Transportation, Bureau of Transportation Statistics
Could you point me to the source on that? I'm curious, because total travel doesn't necessarily equal commute x 2.
My original assertion still stands, though, that for short trips (such as most people's daily commute to work), 70mph vs. 55mph doesn't really 'save' you all that much time.