Part of Lester's big life overhaul involves pursuing the kind of fun and passion he remembers from his teen years—and yes, that effort involves more than just fantasizing about a teenager.
One of his most dramatic moves (in Carolyn's eyes, anyway) is to purchase a 1970 Pontiac Firebird, which is the same bright, passion-y red as the roses floating around his fantasies of Angela.
The car's color is definitely a big clue that the vehicle symbolizes non-sexual forms of passion and excitement that Lester is pursuing as part of his new life. His self-confidence is through the roof when Carolyn first sees the Firebird, as he shouts "I rule!" because he was finally able to buy the car he had always wanted.