Season 3: Episode 64: Say Hello to a Good Buy
Cliff and Theo head for a car dealership with the hopes of replacing the rundown old station wagon. Cliff dresses in old clothes and avoids any discussion of his profession, as he fears that he won't be able to get anything off the sticker price if the salesman finds out that he is a doctor. His plan almost works, until a loud patient runs into him and starts ranting about how rich the Huxtables are. In spite of this, Cliff gets a good deal. Rudy reluctantly accepts Vanessa's advice about her report on animals. Vanessa puts down her drawings and suggests that she cut out some photographs. She fails to specify where to find the pictures, and Rudy winds up cutting up Cliff's encyclopedias and bird books.