The world of car-top carrier boxes is confusing, but the Yakima Rocketbox may be your answer: http://www.yakima.com/shop/cargo/car...cketbox-pro-12. It looks good on a Mini, and while it might not look secure to other drivers, it does the job.

Yes, it will fit on the factory Mini roof rack. It's the lowest-priced of the Yakima/Thule boxes, and boxes are a much better choice than bags (IMO), because the bags sit on the roof of your car-possible scratching the roof or breaking your sunroof. Asthetically, the 12' Rocketbox is shorter and wider than the other Yakima and Thule roof boxes, which fits the Mini body style. Practically, it's kind of a pain to secure on the roof rack-you have to spend a lot of time tightening the hardware to get a secure fit. Even with the secure fit, the Rocketbox will wobble in the wind at highway speeds. I could see this from my sunroof. I noticed that drivers behind me would put a lot of distance between themselves and me, so it must have looked pretty unsteady. We drove more than 300 miles in 11+ mph winds, and the Rocketbox stayed on. From time to time, it did feel like there was more wind resistance with the Rocketbox on, but it was nothing so drastic that it kept me from setting the cruise control to 70 mph.

If you are going to get one, get some extra bungee cords and allow an additional hour to pack the Rocketbox. You need to secure everything inside it or things will flop around.