Since I bookmark way too much stuff, here are some ideas:
Shirts:
https://www.blipshift.com/collections/in-stock?view=instock
https://www.dirtynailsbloodyknuckles.com/collections/t-shirts
http://gearheartshirts.com/
https://enthusiastapparel.com/
https://heelandtoeapparel.com/ (bought their 6mt shirt, great quality)
Art :
https://automobilist.com/ (framed a couple of these for birthdays, and bought the 917 martini for myself. incredible quality.)
https://petrolicious.com/shop (they have shirts, books, decals, etc. too)
https://www.dirtynailsbloodyknuckles.com/collections/poster-prints
https://enthusiastapparel.com/collections/prints
https://linearedge.com/ (wall sculptures of cars/tracks, coasters, etc)
https://carpegear.com/ (kids books + "still/plays with cars shirts", wish they weren't sold out. want this for my nephew)
Accessories:
Leather, laser cut and engraved keychains:
https://www.instagram.com/bruceholderdesign/
https://www.blipshift.com/collections/accessories (keychains and 6mt stress ball are a must)
Detailing stuff: (the mystery boxes could be a cool gift idea, or just gift the stuff you don't want if you're hoping for the buffer haha)
https://www.detailersdomain.com/
http://adamspolishes.com/
https://www.autogeek.net/ (got a bucket set one time. great gift, and you'll use it longer than a year)
Not sure if you're local to any car museums, but gift shops might have some cool stuff or tickets/memberships might make a good stocking stuffer. (Petersen, Larz Anderson, Newport, etc)
F1 fan stuff is off-season, and cheaper.
I've received the TopGear Portfolio for the past 4 years, which is awesome coffee table material. Basically a collection of all their best photographs from the magazine's reviews.