The Toyota van has door cup holder, but it's inconveniently located and angled. If you're storing closed bottles, it works fine but with cups with lids, its just makes a mess.
3D printer to the rescue! This holder slips onto the the headrest support. May fit other other vehicles too.
The holes are 15mm in diameter and 150mm from center to center.
See pics for usage examples.
The main holder will Fit large mugs and cups. The left side is designed to fit the 32oz Yeti Mug. The right side will fit Medium/Large drink cups. With the Adapter ring, the right will fit the medium/small cups. The Basket insert will hold water bottles or other drink bottles that are same size as Gatorade bottles.
I printed this in PLA and have been using it in the van for about a month and a half. Outside temps reached 35C on lot of the days. Didn't seem to affect it. No warping or drooping.
If you are concerned, print it in TPU or PETG for higher heat resistance.