Lower your tires RR
 

Increasing pressure is a cheap way to lower RR and increase tire life. Don't hesitate, inflate.

Smokey the Bear sez: "Only you can prevent HYPO-miling". :p

Seriously, proper inflation and tire selection can make a huge difference.

An old report on low rolling resistance tires available:

Green Seal Report. (pdf version, longer download)

The latest info can be gathered from Consumer Reports. They consistently test new tires, but require a subscription to access the data. Libraries may have the issues for free...

RH77