www.mpgresearch.com is a dedicated forum, dedicated to fuel efficiency (which is different than fuel economy, though they're related). However, it's been "taken down" numerous times, and is down right now.
My '79 Honda CB650 SOHC4 motorcycle regularly gets 65mpg. When I got it, it only got 35mpg. My '98 Ford Ranger got 36mpg in town just by watching my ScanGauge.
The problem would be getting the power chasers to go the opposite direction... And when the people that
have been dedicated to fuel efficiency try to voice their ideas, they generally get shot down pretty quickly (read the
100-mpg car $10 million cash purse thread)...