Green is correct if it's coolant you're smelling. However, I had this problem once on another car. It was indeed gas I was smelling. Check for leaks in the fuel lines going into the fuel injectors. That's where my problem was. Nissan replaced mine free of charge due to a recall, but if it's faulty fuel lines, I would suggest calling the corporation and letting them know of the problem. They may replace it for free rather than have you call the feds to report the problem.