Worried that carrying the bike outside using a trailer hitch or strap on rack would mess up the aerodynamics?
If that was addressed to me and not jlv, that, plus it's more hassle than it's worth for a single bike. I've got roof racks, and when my friend and I take our bikes on a trip we use his 4Runner instead of my Forester, because he has a hitch rack and I don't, and the gas mileage is about the same as my Forester with bikes on the roof.
When I bought the Forester I considered getting a hitch rack, but the only hitches available for it were for 1.25" rather than 2" balls IIRR, and the Yakima sideways swing-away hitch mount I wanted needed the latter class (tongue weight issues). Given that and that I preferred not to be hauling the weight of the hitch around all the time whether I was using it or not, I went without. Truth to tell, I haven't used the roof racks in years, and I've taken the car rails off the roof as well (except when I need to carry a kayak). With the back seats down, one or two pairs of skis will fit diagonally inside with gear no problem, even my long (210 cm) X-C skis, and as I'm not a scoutmaster anymore I haven't needed to carry more than two pairs for a long time. A Bolt being 11" shorter can't do that, although it might be possible to carry them lengthwise between the front seats.