My reasoning: Tesla has vehicles (for sale or in plan) in three segments: high-end sedan, CUV, and mid-range sedan. Building a coupe would fill another segment.
Also, the 2-door market has lots of models (2/4/6 series, C/E/S class, A5, CTS) that are priced high. Attracting higher income buyers to Tesla from these companies with a 2-door would be a very logical next step.
D = dual, as in dual door?
By the way, what happened to Model X?
Not too bad for a new design.