Back in 60s/70s we had an old VW type 2.
We used an lpg gas convector heater all plumbed in with copper pipe,
There were many reminders to have good ventilation, again as someone said earlier it really boils down to common sense and not leaving it on all night.
Then after around 8 years we got a Merc 206d (which we had for 14 years and not a spot of bother) that was originally a Hannomag and I duly fitted a catalytic heater in it again all copper piped, the main problem was it was an absolute pig to light it.
At that time it was reckoned they needed even more ventilation than the normal flamed ones.
With friendly greetings,
Ian and Eileen