Possibly. It's been a few years since I looked at it in detail, but it likely rules out a hardware upgrade for the car as you will already have the later modem.
The fundamental issue is that mobile operators have limited spectrum to play with, as 4g and 5g are deployed they tend to retire 3g to free up the spectrum, sadly cars are not represented replaced as quickly as phones.
To that end most big networks plan to keep 2g service for a number of years, as it is still the best for penetration. 3 don't have that option as they never had a 2g network.
I'd try a different SIM, suspect it will just work.... if not, you will have lost a tenner max
