I fixed one burnt car in my 35 years of fixing cars. A 1981 Grand Prix. All was going well until I found the computer wiring harness. That was my first experience and the last. As far as the smell, I gutted the car completely, I mean everything and took it to a power wash and pressure washed all the air flow areas, cowl, everything I could wash and never got rid of the smell. I told the person I sold it to the previous owner was a fireman and that is why it smelled. (Just kidding)! Told them it had a slight overheating problem. (got ya again).