Gang,
This past summer we vacationed with a road trip out west from the Midwest. We drove our 03 350Z 7000 miles and the car averaged 28MPG and change overall. That included the mountains and the flat lands and speeds from 65 to 80+. Plus it also included spirited driving from San Francisco north to Oregon on the coast highway (Route 1)
(That highway was a ball in a Z). There were several tanks that we got over 32. In the thin air of the Rockies we were down to tanks at 24MPG. Pikes Peak was a blast of a drive also (wife didn't like the the white knuckling).