Standard 32 page color children’s book with illustrations. I believe the boy was sickly. One day his cockatoo (or parrot) flew (or was blown?) out the window, and he and his chauffeur or butler drove all around the country looking for the bird. As they went, parts of the body of their car kept falling off, and they kept having to replace the parts with colorful, non-matching parts. Eventually, I think they found the bird.
Sounds like The Last Time I Saw Harris by Frank Renkiewicz
When a fierce windstorm blows away his clever parrot Harris, Edmund is inconsolable and goes with the family chauffeur on a long search through town and country.
https://www.goodreads.com/book/show/676108.The_Last_Time_I_Saw_Harris?from_search=true&search_version=service