Can include non-starters as technically they entered but never raced and tests that never went anywhere.
I remember a few from the 2003 Champ Car Season:
The stillborn BC Motorsports team that intended to run Giorgio Pantano.
F3000 teams Arden and the short-lived Brand Motorsport were linked to entries, the latter would have brought back sometime Chip Ganassi driver Nicolas Minassian, the former could have had something to do with the fact that one of their drivers that year was Townsend Bell who had previously driven for Patrick Racing.
Kurt Busch tested for Team Rahal but Bobby Rahal had already signed Michel Jourdain Jr.
Andre Lotterer was linked to a full-time switch to Champ Car after driving for Dale Coyne Racing in the final round of the 2002 Season.
The late Justin Wilson was linked to Newman-Haas Racing before signing for Minardi in F1.