Chevrolet - Equinox :: Getting Outside Odors When Inside Circulation Is On?

We've noticed that when we have the inside air circulation on, we're still getting exhaust fumes from outside the vehicle and other "smells", too. I've never had this problem before and the dealership (and manufacturer) say that it isn't air tight and we would still get outside odors coming in. I don't accept this answer. We've never had this problem on any other vehicle we've driven. My husband has heart issues and when exhaust fumes still enter the car, it effects his heart. The only way to stop odors from entering the vehicle is to turn off the fan - but that creates other issues (especially with fogging up windows, etc). So, how do we remedy this? We've taken it in for maintenance, and they say everything is "shutting/securing" as it's supposed to be. There's no leak anywhere else. We don't accept this answer (and even one of the service techs say it shouldn't do that, but when they're told by the manufacturer that's what we have to tell the customer, that's what we have to do). My husband hates to ride in the Equinox now due to this problem. We've read up on the "Lemon Law" and may have to enforce it.