These car coasters are made of a neoprene material which makes it a perfect accessory for your car.   The durable fabric is easy to clean and also has a non-slip suface.  The neoprene material helps cups not spill but also absorbs condensation from the outside of the cup keeping your car clean and damage free from sweating cups.
 
Many options to choose from.  If you don't see a design you like I would be happy to create one for you.