Just returned from our first long family vacation trip and the RDX did great. We did about 2700 miles over 10 days.
Loaded up, with two bikes on the back, we got 26-28 MPG on interstates at 70 to 75 most of the time.
In the middle of our vacation, I took a 240 mile trip (one way) unloaded without bikes and got 31 one way and over 29 coming back.
We are very happy with our purchase.
My TSX still averages about 2+mpg better than the RDX overall in mixed driving.