In addition to our vehicle vibration problem (see epic rant posted) our horrible GMC Yukon XL also lets almost all external smells through when we are using the recirculation feature on our AC. With over 25 new cars between my wife and kids over the years apparently we were "lucky" to have other cars that kept out most exhaust smells from cars in front of us at stop lights when we used our recirc features. Well, apparently GM cars are "different" because most smells, to include someone smoking a cigarette in front of us at a red light, come straight through into the cabin of our Yukon while using the recirc feature and our friends at GM say this is normal and went on to explain how all smells would not be kept out (blah, blah, blah). We know that but shouldn't some smells be kept out like it is on all the other cars we have owned in our life? We have even had GM cars that didn't have this issue but our regional rep at GMC and local dealer say ours is normal and they have no response when smoke smells come straight through the cabin. Our car is complete garbage and I guess we got what we deserved for buying more GM garbage because they refuse to fix anything because to them everything is normal.