Yes, somehow it is. The 1800/2100 was still designed at Fiat, but still just before establishing the Styling Centre (when cars were styled by engineers
![Wink ;)](https://www.autopuzzles.com/forum/Smileys/default/wink.gif)
). Giavosa was not totally happy with the results and therefore asked Pininfarina to make some little improvement. The 404 came just later.
But, generally, Pininfarina was rather used in re-proposing the same style on different cars. Think about the Corvette Rondine that becomes the Fiat 124, or the Lancia Flavia, developed from Fiat concept-cars. But the most important si the Alfa Romeo 164 and Peugeot 605. However, in this case there is also some legal dispute behind and that signed the end of the cooperation between Pininfarina and PSA.