the last time i went to CO i was in my beater honda. and i drove 55mph the entire way there. something like 41-42miles a gallon.Well that means mostly I-70 for the majority of the way which I believe is anywhere from 60mph up to 75mph (I'm not doing 75mph in my diesel TJ, well hell in a TJ period).
The one advantage to doing around 65mph is how much ground we can cover each day depending on the time we spend on the road as well.
-Grant
when you factor in how much fuel is burned. theres no real advantage to going 70 cross country in a car. unless youre in a diesel and you can chug along at 70 around 1200rpm. 70 = more stops for fuel more time standing still.