Yes Bill, you are right, Mileage can be less than epa ratings. I tried to do some research and could not find the epa ratings on a lot of suv's because, they are rated as trucks and don't have to supply them....go figure.
I went to consumer reports and found some intersting #'s....BTW, I only look at city #'s as 96% of my dirving is in the city.

Durango 8/13
Aspen 8/20
tahoe 9/19
armada 9/19
Navigator 8/18
Hummer H3(small?) 10/20
Xterra 12/23
Escape 13/26
BMW X5 12/22

Granted, they drive these cars hard, and driven as carefuly as most people drive a hybrid they would probably get better mileage say 20% which would bring the Durango or aspen all the way up to 9.6 mpg. I have found a lot of people with the large engine push it hard because they can and, well it is fun.

So, Lets say that same person gets 30 mpg from a Hybrid, I have found many people with hybrids nurse it along for the best mpg, cause, well they can and, it is fun. Which is going to have a lower fuel cost per year?