P1057 Expandable & Collapseable Cup Holder: $10.95
This Cup holder is a perfect match for your Miata!
Made of BLACK grained plastic to match other parts of the interior, it adjusts to hold any size can, cup or mug. And when not in use, it folds up to just 3/4" thin!
Mounts using an existing hole, plus one through the carpet, so that it does not leave marks if it is ever removed.