Engineering Explained, Everyday Driver, Petroliscous, and TRDheadquarters are the ones I regularly keep up with.
+1 on TaxtheRich100, for not only the crazy awesome 288 GTO video, but for also learning about another use of the Ferrari F50 rear wing...
https://www.youtube.com/user/19Bozzy92 - raw racecar sounds and videos from somewhere overseas
https://www.youtube.com/user/TEDtalksDirector - various TedTalks
https://www.youtube.com/user/simonscat - Simon's Cat
https://www.youtube.com/channel/UChtY6O8Ahw2cz05PS2GhUbg - Make