In order to get to our slalom events I sometimes need to carry 8 wheels since the conditions may vary (dry & wet).
So, I made a roof rack which can carry 3 wheels, since a trailer is not legal (if the manual says no, then our authorities won't allow it either). Also, with a trailer the speed limit is lower and there's no speed limit reduction with a roof rack.
3 wheels can be placed on the roof, 4 on the back seat and 1 in the trunk.
I primarily used the Yakima roof rack components suggested in this thread:
http://www.ft86club.com/forums/showthread.php?t=15028
I needed to reduced the dimension M2 from 4" to 2.5" and reduced the dimension M3 accordingly. (The sheet metal in the back is a little soft that far back.)
And I also purchased these SNARs in order to fix the part which carries the wheels to the roof rack.
https://www.etrailer.com/Accessories.../Y8810135.html
I added 3M polyurethane tape 8672 on the roof where the rubber pads are in order to protect the roof and increase the friction coefficient between the rack and the roof.
Fuel consumption at 120 km/h (75 mph) goes up by about 30% with those wheels on the roof (which also shows how aerodynamically efficient this car is).