Two factors never taken into account in any of the EPA estimates are :

Cold weather driving which will lower the 'annual' combined estimates by 7-12%;

Weighted averaging of Hwy vs City driving. EPA assumes 50/50 as a best guesstimate.

Now in mild weather which approximates the EPA testing criteria and driving 85% Hwy / 15% City, I'm just under the EPA 'weighted average' combined value of about 52.5 mpg. This I attribute to a somewhat heavy foot on the Hwy ( 60-65 avg ).

While I pay attention to driving methods I don't go to any special extremes. The technology does what it's supposed to do.

Regards the TCH, I'd feel very confident that any knowledgeable driver that wasnt seduced by what will likely be a more powerful drive will attain 36-40 mpg easily.

Lifetime fuel usage: 2.1 GPC ( 1.99 recent )