On my 06, I measured out to about 46 mpg Dual Sporting on a relatively flat road. 5 th gear just chugging at 45 mph. Haven't checked the 09 yet since the rejet, AP spring, and YZ Exhaust.
But I did accidentally go about 205 miles on a 3.6gal tank with the crazy lean stock jetting and exhaust. All cruising at 40-45mph mode, 50/50 mix asphalt and hardpacked dirt, which is probably the most efficient way for it. I know that racing an enduro I get about 25mpg.
There are a ton of variables involved. Jetting, tire pressure, extra weight being carried, hills to climb?, gearing, how you apply the throttle, quality of gas, etc....
I expect to get around 40mpg with 09, b/c I have it snarlin' a bit more that the 06. Although I will be trying a 48 tooth rear sprocket, which should have it turning less RPM at my 45mph cruise speed.
Edited by Bandit9, November 08, 2012 - 07:35 PM.