Roof rack and mileage decreasing

Did you keep track of your fuel economy of the last car with a roof rack? We could calculate an estimate from that.

 

Don't expect any less on a Prius. In fact, expect more loss, because while your new car has improved efficiency and aerodynamics compared to its predecessors, racks and the stuff carried on them will be unchanged, thus will be responsible for a greater fraction of your total fuel consumption.

Hitch racks on a Prius are also lossy, as most of the bike structure is not in wind shadow, but out in the full wind blast. With bikes loaded, mine costs at least 15%. And I don't drive as fast as average traffic in your area. When cargo permits (which isn't often), I put our bikes inside instead.

 

Depends a lot on speeds involved too, I would think.

 

This was from an article I just read:

Consumer Reports tested a 2013 Honda Accord at a steady 65 mph. With nothing on the roof, the car got 43 mpg. An empty bike rack cut that to 38. The fuel economy dropped to 27 mpg when two bikes were attached to the rack.