Probably a lot of overlap here:
Subscriptions:
French 'Sport Auto' 1973-1977. Kept them all but have lost a few 'lenders'
'Autosport' 1976-1998, but I've only kept complet volumes1976 through 1984
'Flight International' about 1988-1998, kept a few selected issues and lots of the cutaways
'The Aeroplane' 1995-2001, have kept many of them
'Aviation Week' 1988-1997, have kept a few selected issues
'Motor Sport' 1998-2006 have kept most of them
'Race Car Engineering' 1997-2009, have kept many of them
Danish 'Veteran Tidende - bilhistorisk tidsskrift' since 2018 - . It comes with the Dansk Veteranbilklub membership. Actually quite good with many interesting articles of historic interest, latest issue one about Danish-bodied pre-war DKW cars, last month big features on the Hillman Imp. I wrote two articles for it about Opel saloons of the late 1930s last year. It's also very nicely produced, usually runs to about 60 pages with very few adds.
Danish 'Flyvehistorisk Tidsskrift' (Danish journal of aviation history) since 2014
Swedish Allt om Hobby 2014-2017 kept all. Nicely produced Swedish almost-monthly about all things modelling - subscribed back then in an effort to lure my son away from the computer screen...
Occasional buys before and/or after subscription of all of the above, and of the following, in no particular order:
Alpha Auto (mid 1970s)
Air International
Flypast
German Sport Auto
German Rallye Racing
Motor (UK)
Autocar
banen (now defunct but well-produced Danish mag about all things (mostly Danish) railroad and rail modelling related)
Racetech Magazine
The Automobile
Automobilsport (nice German historic motorsport publication)
Autosprint
come to mind.
I have most of the 1950s issues of the now defunct Skandinavisk Motor Journal, a rather nerdy, now almost cult, motoring monthly inspired by the German pre-war Motor Kritik of Josef Ganz.
One publication that I regret never subscribing to is the now defunct Automobile Quarterly, even if it is naturally quite US-centric. I have a few (too few) issues, all with very interesting and well-produced articles and I'm on the lookout for more...