I have a Yakima roof rack with steelhead trays for both road and MTB. I've used them on SUVs which are a pain due to height. I couldn't handle putting MTB inside SUV because of smell from dirt, mud, deer droppings, etc. High end bikes on a hitch isn't something I'd consider anymore than using my bike as a bumper pad and issue of having 1/3-1/2 value of car hanging off the rear bumper.

If you don't care about Civic vs. Prius, definitely nice to have hatchback to throw in a single road bike. Downside of roof rack is I have tons of friends with stories about driving into garage fully loaded (ouch).

Other downsides:

* Noise - roof rack alone adds a huge amount of wind noise and rack alone lowers mpg by 2-3 on freeway
- had to add wind shield because the wind drone was awful
* MPG - w/o bikes = loss of 2-3 mpg at 70mph, more at higher speeds
- w/ bikes = loss of 5-8 mpg at 70mph

That makes driving with MTB on top driving up hills (and I'm usually late so have to drive faster) and AC on gives me 24-26mpg or around 33 normal freeway driving.