And, to add to the list:
A. Fix the friggin' NVH issues--a Model S should be the quietest interior on the planet.
B. Automatic GAIN on the radio's volume, aka "speed dependent volume." As the speed increases the issues in A. make the radio hard to hear . . . .
C. Shrink the door sills--they don't have to be as huge/tall with better crash safety software enhancements, and better use of material science advances (i.e. better metal).
D. Coat hooks. It's been almost NINE years and we still don't have them in the S?!?
E. Landscape format for the MCU, at 17" or larger, and keep the IP display in front of the driver too please.
F. Ditto on the Model S loaners. Buying a six-figure car and hearing, "Here are some Uber credits" just doesn't cut it . . . .
G. Bulletproof reliability, across the board. That means TEST, TEST, and TEST some more. Set up stronger warranty provisions with suppliers so that they too learn how to adopt Deming's Quality principles.
H. Consider inflatable A-pillars so they can remain shrunk until an impact (see recent patents on this) as the current pillars are huge blind-spot makers.
I. Interior materials should be better than Impala standard, especially the door seals. It seems every YouTube video shows a curled up window seal behind the driver . . . .
J. Paint that looks like you can swim in it.
K. Heated armrests--those would be cool.
L. Fludetic(sp?) washers, a la any Ford from the past few years?
M. Individual wiper motors, one per side, a la the Ford Fusion. Less noise and friction, better range.
N. Upgraded steering wheel rollers; current ones have a cheap feel and similar actuation.
O. Laser headlights.
More to follow . . . .