You can travel to Boulder, Colorado and hook up with hybrid plus. For something like $36,000 you can have a state of the art plug in hybrid battery. Our own GPSman1 has driven this setup and achieved something like 140mpg in the urban setting and 90 mpg on the highway.

Hymotion is another option with a plug in battery that piggybacks onto your current hybrid battery. This setup takes up a portion of your cargo space.

I'm assuming it will be another 18-24 months before the plug in hybrid batteries start to become "available" on a few new models.

2005 AWD Escape Hybrid
Best tank trip MPG 39.02 (scangauge II) for 402 miles on I-70, 10.3 gallons used over mostly flat terrain.

Best tank trip MPG 34.6 for E30 for 271 miles along I-80 in Indiana and Ohio.