Re: Volkswagen GX3 Concept
Plymouth had a four-wheeler that looked vaguely like this (more retro than futuristic). Car's name was Prowler, and it did horrible in sales and was discontinued very quickly. Miata on the other hand is a definite sales success, and even though it is also a roadster, it is a joyful little car to drive (looks quite unsafe to me, but thats just me).
Bottom line, roadsters bring some variety to a line up but they are neither big sellers nor are very practical.