Article on how roof racks change car mileage:
My mileage was different. With my old 2001 Subaru Outback, if I had the cross bars off, I was getting 28-29 on freeways. Put crossbars (Yakima round bars) on, and it dropped to the 24-25 range. Put something on crossbars (kayaks or bikes) and it really didn’t seem to change from what I found with cross bars on (maybe drop 1mpg). Never tried inflatable unicorn pool toy.