Lack of proper cup holders! Something like the E46 ones (next to the handbrake, interchangeable with storage compartment) would have been ideal. Luckily the Machine Monkey solution seems to do the job 
(Disclaimer - I only use the cup holder for a water bottle, no other food or drink is allowed in my car!)

(Disclaimer - I only use the cup holder for a water bottle, no other food or drink is allowed in my car!)