Having the clearance of, say, an Outback is great every...not so often. Getting into Darrington or Depot Creek comes to mind...but the reality is that clearance, which costs you a pretty penny, only saves a handful of miles of hiking a year at best. A mountain bike can usually make up the difference in a far cheaper manner. Unless you're a real desert rat, that is.
The real question concerning a road trip vehicle is:
Do you carry more than 2 folks often?
Do you want to be able to sleep in the vehicle?
If no to both, just about any vehicle with a rocket box will do the job just fine, for way, way less many than your standard overprized, overconsuming SUV. Hell, even a Civic or SmartCar would be just hunky.
It seems, regarding this vehicle, that 22 mph is pretty poor, considering where gas prices must inevitably head in the near future.