Leave it to an BMW roadster owner to come up with a solution to the cupholder problem. What you are looking at is good old ingenuity, this is nothing more than a section of 3″ PVC pipe, precisely cut to fit inside the side storage area. A couple shots of semi-gloss black spray paint and that’s it, you’ve got a cupholder that blends nicely into the Z3 interior.
This design is simple, functional and cheap (which is the kind of combination I like). If you want to go the PVC route you can visit the local hardware store and then spend an hour or two cutting the PVC to get the fit just right. Total cost is probably going to be around $5, however if you aren’t the do-it-yourself type you have another alternative. This original cut PVC pipe design was used by HMS Motorsport as a prototype for a nicer plastic/rubber moulded cupholder. The HMS cupholder is nearly identicle in shape, except the flexible rubber material makes it easier to snap the cupholder into place. The HMS version is now selling for $24.95, so its roughly $20 more than a home made version but all you have to do is pick up the phone instead of spending an hour or two of your own time making one from PVC pipe.
The design works quite well in that they hold typical 12oz cans, and the larger skinny 20 oz plastic bottles, however it doesn’t work with fastfood cups. About the only other complaint I have is that condensation from the can could drip down into the side storage compartment (and sometimes I have other stuff in there). I’ve learned to keep something like a napkin under the cupholder just in case.