I've considered it my self, in my car, even bought a mini 800W generator but decided not to use this method, or CO at all.
I think it could work with both types of generators, you can test it with a CO detector to verify CO levels are higher then 7500PPM inside car/room. But the generator better be out of the car/room with the exhaust gas directed inside by a pipe. There are a few reasons for this:
- Some generators today are equipped with a CO detector that automatically shuts them down when CO levels rise.
- The noise will be unbearable.
- It might consume all the oxygen in the car and shut down (Paradox here- but still might leave enough oxygen for human to breath)
All though there were cases of generators inside cars that succeeded:
https://pubmed.ncbi.nlm.nih.gov/7832611/