The Drews DKW and the "Hartmann Spyder" are the same car which was modified many times throughout its life. Joachim Drews lists 12 different versions of this one-off in his book about his family's coachbuilding company. After the Spyder was shown in auto motor und sport 3/1957 where Hartmann claimed that it was his own creation he was forced to state a correction that the bodywork was designed and built by Drews (see below).
Allemano's picture shows the first version which remained unpainted until it was modified for its buyer (probably Fritz Trump, responsible for DKW exports at the Düsseldorf factory). The bottom right picture in reply #15 shows a rear view of the first version, while the top right picture (as well as the on in reply #18) show the second version like it was sold by Drews in 1956. Alfred Hartmann bought that car in 1957. The pictures in replies #22, 17 and 21 show versions 3, 4 resp. 5 while it was owned by Hartmann. The other pictures show the car after it was restored by Drews in 2008.