The weird thing is I'm getting around 15.2 mpg whether I'm going to work or out on the highway. I do find it hard to keep the X under 80mph when on the hwy because it's so smooth but the last time I drove down to Temecula I was mostly going 65. The next pure hwy miles that I do I'm going to concentrate on just cruising.

As far as PSI goes the tire max is listed as 44, and my friends all say to run the max if you're doing pure hwy driving if you don't mind the harshness.