You never used to salute people in their own cars due to CT
Yes this has varied in the time I’ve been in RAFAC (I go to an RAF station a lot in civvies in my own car for flying club stuff and now, I do usually get saluted).
(and if I don’t, it’s usually by someone older e.g. MPGS who probably isn’t being disrespectful, just has forgotten the policy has changed)