I've been looking through this thread occassionally and I think it is time for me to comment and share my thoughts.

THIS LIST IS INCREDIBLY SPORTSCAR BIASED

There are a lot of iconic sportscars out there, but there are many more iconic cars out there that might not be as glitzy or fast. Here are some German cars which are iconic IMO and deserve to be on that list. Again, IMO.

Audi
Horch 853A
Quattro
Sport Quattro


BMW
327/328
Isetta, 600 and 700
502, 503 and 507
2000 CS / 3.0 CSi / 3.0 CSL
M1
635 CSi M
2002 Turbo
1985 M3 & M5


Mercedes-Benz
SSK & SSKL
500K Spezial Roadster
540K
770 Großer Mercedes
300SL Gullwing / Roadster and perhaps the 190SL
Pagoda SL
300SEL 6.3
450SEL 6.9
450SLC 5.0
190E 2.3 / 2.5-16V


Opel
Rallye Kadett
GT
Manta
Rekord D
Monza


Porsche
356
901
911 / 912
914
Carrera RS 2.7
Turbo (original)
959


Volkswagen
Beetle
VW Bus (1950s)
Karmann-Ghia
1970s Golf


To me, the Pagani Zonda is not an icon, YET. In a decade or two, perhaps, but not now.