"If S were to" vs. "If S should"

English as a Second Language English Vocabulary, Grammar and Idioms
5
  1. If you buy a car, it will cost you a lot of money. (It is entirely possible for you to buy a car.)
  2. If you should buy a car, it would/will cost you a lot of money. (It is unlikely or not particularly probable that you will buy a car.)
  3. If you were to buy (=bought) a car, it would cost you a lot of money. (It is impossible or less probable that you will buy a car.)