Regarding Auto Emissions I believe their should be none. Florida has no auto emissions regulations and we are getting along fine without them. Regarding oil drilling and refining. I believe their should be regulations but not so tight as to basically keep plants or drills shut down. I believe they should be monitored so the enviroment around the refineries or drills isn't badly affected.
Umm ... if all 50 states (or a majority of them) were to remove their auto emissions regulations you would likely see a change. Right now the auto makers design vehicles to meet the needs of the majority of consumers. If they could cut out emissions requirements to make a cheaper car they would. And odds are we'd feel it.
Secondly, I agree with you regarding environmental standards regarding drilling and refineries. They should be monitored and if it is badly affected, they should be shut down. I believe that is where we are at right now.