As discussed in the Non-Unidentified Vehicles thread for the 159 'Alfetta':
158 'Alfetta' .. same logic it was always an "official" nickname
https://www.imcdb.org/vehicles.php?make=Alfa+Romeo&model=158+Alfetta&modelMatch=- 1&modelInclModel=on
^I still have my doubts for one of those...

plus.. these were not called ''Sprints'' but simply 1900 C Cabriolet Pininfarina . C for corto -short chassis.
http://www.imcdb.org/vehicles.php?make=Alfa+Romeo&model=1900+Sprint+Cabriolet&modelMatch=- 1&modelInclModel=on
http://www.alfacompanion.com/alfa1900/photobase2/gallery.htm