The answer is quite a lot.
Here we have two quick pictures we snapped over the past little while of our Wego 500 loaded up with gear. This vehicle roof top cargo carrier is over 78 inches in length, 15 inches in height and over 32 inches wide. The top picture of the Modula Wego 500 is loaded with an avalanche pack, two snow boards, a wooded toboggan, two jackets, snow pants and helmets.
The bottom picture is also the Wego 500 roof top carrier loaded with a duffle bag, laptop bag, two cooler bags two motor cross helmets and two snowboarding helmets and plenty of room to spare.