I traded my X3 for a used RDX. While the X3 was a good car, it's reliability was waning after 100K. The RDX was a great choice. Reminds me of the X3. Ride is about the same (choppy over rough spots) but handles even better than the X3. Seems roomier and gets a bit better gas mileage. Sure you can get low miles if you keep your foot in the turbo. I'm getting 23 to 27 on the highway and 19 in town. This is the AWD version too. I have an MDX that's been a reliable car. I expect the RDX to follow suit. It's a great car for one who enjoys driving and isn't put off by the tight suspension. Plus it's an Acura.
Is roomy; handles great; accelarates well; nicely built; good quality; good value
It should be possible to engineer the car for a smoother ride...perhaps a cruise and sports mode that adjusts the suspension.