Student or Learner
Mercedes-Benz has been overshadowed by Ford and Lexus, who are the brands...
(I'm not sure about Ford being in the list, so it may not be the actual brand named in the programme)
(English4U, TV Channel)
Is it justifiable to use 'who' here?
I would use which, but who doesn't sound wrong to me.
I'd use "which" too, but if the rest of the article is about the people who are making things happen, "who" could work.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.