I have a 2017 Nissan Altima Special Edition Law Enforcement, the exhaust fumes are coming through our AC vents and doors in our vehicle, the AC vents it can be on recycle or out air either way we have to ride in our vehicle with our back windows down plus my wife as we speak is going to the hospital to get Radiation as we speak plus it gets very strong smell inside our vehicle it is Very Hard to Breathe, I am taking our vehicle to a paint and body shop, very soon!!!
A non-chain muffler shop would be better than paint and body shop.
As an ex-law enforcement vehicle it probably does not have a warranty.
Get it to a shop ASAP, use a taxi or ride service.
I suspect that you are not in the US because I don’t know of any Nissan Law enforcement vehicles here. You need a muffler shop to look for exhaust leaks This thing is not safe to drive .
I was wondering about that too, Explorers and Chargers where I live, a few Impalas and Crown Vic’s still around.
If this vehicle has been in a collision it is possible that one of the cabin vents in the rear of the car have been damaged. If one of the cabin vents is missing or damaged exhaust can be drawn into the car especially when driving with a window open.
Remove the rear bumper cover and inspect the cabin vents.