[chime]

How about bike racks in the back? I wonder which placement is better for mileage due to aerodynamics: Top or back?

[bencpeters]

I generally do 2 in the back on a hitch rack, and 2 on the roof on my Subaru right now.

(but I realize that car shuttles requiring 4 40lb downhill mountain bikes isn't exactly your typical use case for a car! It's just an important part of what I personally need it to do...)

In my experience, bikes on the hitch rack hurt gas mileage less than the roof ones, but I haven't been super rigorous with the comparison...

[avn2109]

But... ski racks! So important for some people, and there's nowhere for them to go except on top.

[chockablock]

There are plenty of hitch-mounted ski racks (skis are held vertically).