my recent fill up:
34mpg, 160miles on freeway cruising at 65mph, (me + 2 passengers in car)
Technique I use:
get it rolling in 1st, then immediately into 2nd
50-75% gas, shift into 3rd around 3,000RPM
give 75% gas, then shift into 4th around 2800
give 75% gas, then shift into 5th around 2800
You'll have to shift pretty quickly to do this.
Do not give it 100% gas as that might tell the computer to enrichen the fuel mixture.
Contrary to common beliefs, higher throttle opening isn't bad for fuel economy, but letting it rev high in each gear is.