"Много" is not a genitive form of adjective "многий" — these words are different parts of speech with the same root.
"Многий" is used only in plural form, "многие". It means "many" (or, to be precise, "many of"):
Многие машины в России — с правым рулем. Many (of) cars in Russia are RHD vehicles.

DAMN! I came the the second — again!