You do realize that UK didn't give Rupp a Cadillac, right?
Link: Rupp, Bear Bryant the Cadillac and the Lighter
Rupp did receive a Cadillac, but it was in 1955 (well after Bryant had already left UK and had started his jokes about receiving a lighter) and it wasn't given by the University, but by school boosters in commermoration of his 25th year as coach at the school.
I've always said that if Bryant had stayed at UK for 25 years, I have no doubt that boosters would have been willing to purchase him a Cadillac as well.