When taking the Fiat 127 as Manzu's most famous works, it is indeed older.
But it is younger than his also well known Austin Healey and is from around the same time as the Autonova GT and Auto Fam.
The name hasn't appeared yet on Autopuzzles. Car design was absolutely not the main activity.
As far as I know, there is no connection to Zagato, but perhaps the designer took indeed some inspiration from it.