Since I use my Roadster to commute everyday, I have been missing a functional cupholder and a cell phone mount for my iPhone 5s. Here is what I did ---- very inexpensive yet very functional my purpose. I keep the cupholder and the phone mount permanently in its place, and it hasn't bothered my passengers. Both my coffee mug and iPhone are super accessible from the driver seat.
CUP HOLDER:
Amazon.com: Trademark Poker Jumbo Aluminum Poker Table Cup Holder (Black): Sports Outdoors
IPHONE MOUNT
Amazon.com: iOttie HLCRIO102 One Touch Windshield Dashboard Universal Car Mount Holder for iPhone 4S/5/5S/5C, Galaxy S4/S3/S2, HTC One - Retail Packaging - Black: Cell Phones Accessories
CUP HOLDER:
Amazon.com: Trademark Poker Jumbo Aluminum Poker Table Cup Holder (Black): Sports Outdoors
IPHONE MOUNT
Amazon.com: iOttie HLCRIO102 One Touch Windshield Dashboard Universal Car Mount Holder for iPhone 4S/5/5S/5C, Galaxy S4/S3/S2, HTC One - Retail Packaging - Black: Cell Phones Accessories