I've been able to beat the EPA since I got my 08 HCH-II despite crappy terrain. First week or so I was getting 45mpg into work, 35mpg back, then quickly upped to 50-55 in and 40 back for a first tank average of 45. Second tank 46, still improving, but as I got used to the feel of the car I got a nagging feeling.
Bumps felt kind of "gooshy" - I knew the feeling from my old Jeep when it got a slow puncture. Checked the pressures. 40psi. Drove a bit more, checked again. 40psi. Pushed on the tires with my fingers, peered at the profile. Just not convinced.
Got myself a new pump/gauge over the weekend. Checked with a third handheld gauge.
Both of the other gauges read 26psi.
So yesterday I got all four wheels up to a REAL 40psi, and long story short I'm getting about an 8-10% improvement in mileage.
The car just saaaiiillllls along now.
Now I'm just waiting for a good traffic day to get that elusive 60mpg inbound commute. If I was able to get a best-effort 58mpg on crappy tires then I'm hoping to kick a$$ with some overinflation
Lesson - double and triple check pressures.