I went from a 2007 CRV to a 2017 RDX, everything improved except the rear cargo space. So to add storage I purchased a Thule 16 square foot cargo box. I had to add attachable rails, mine are Rhino Rack rs-2500 airo bars. My RDX did not come with roof rails. I just took it for it's first test run, no hick ups. Milage was just over 27 mpg according to the trip computer, four adults and all our camping gear. On a different trip with the same four people and just our luggage the trip computer showed just over 29 mpg. So it looks like I lost 2 mpg. I was looking at a cargo box that attached to the trailer hitch, but decided to go this route. Despite the loss in arrow dynamics I thought it would be better to spread the extra weight over more of the car instead of just the rear axels. Happy trails!

 

That looks super cool aka “bat mobile style”. .