More like 'Why don't we have bubblecars any more?'
Behold the Volkhart-Sagitta. Cd of .17 in 1940. Splash a mold off that, heck snap some pix in the museum and then output it with a 3D printer. Drop it on the ubiquitous VW floorpan and put a TDI diesel in the tail.
Take a look at
Local Motors