“I would buy a new car and house if I was rich.”
Actually, the formal grammar rule states that in present unreal conditional sentences, the verb in the condition statement (“if I was rich”) is changed to a past tense verb, but the BE verb is irregular, and thus changes to WERE no matter which pronoun is used (we, they, she, he, I). The irregular form is what is problematic for most native speakers (although they might not realize it is incorrect), and within a few years, this usage might become completely acceptable. Now, share your ideas. What grammar rules do you know of that seem to be used differently from what we found in formal textbooks?