I’m posting this here because I could not find the MINI Cooper Clubman S Cargo dimensions ANYWHERE else on the internet. So, here they are!
Mini Cooper Clubman Boot / Cargo Dimensions
The largest single box-shaped object you can slide into a MINI Cooper Clubman (S or otherwise) is 24″ (61 cm) tall x 32.5″ (82.55 cm) wide x 60″ish (1.52m) long, depending on how far forward the seats are. The MINI Cooper Clubman S is (as you can see in the photo above) rather wider at most points, but the rear suspension towers stick out into the cargo area a bit, reducing the size of the largest single object you can fit.
The largest single flat object you can slide into a MINI Cooper Clubman OVER the strut towers is 38 1/8″ (96.83 cm) wide, but not very thick, since the back doors curve so that they’re 32″ wide at the top corners. I also didn’t do much checking for the possibility of sliding something long and flat and wide in diagonally.