Books are of their time and get dated regardless of what we do. Technological and political change, changing social attitudes and yes, brandnames, will eventually catch up with our works. And that's okay. Jane Austen's novels are full of dated references to the fashions and popular culture of her day and we still read them 200 years on. Indeed, there are some late 18th/early 19th century authors who are only remembered, because Austen's characters discuss their books. Or in the case of August von Kotzebue, he is mainly remembered because he became the victim of a political murder and because Jane Austen's characters perform one of his plays.
Meanwhile, authors desperate not to date their works often turn out stories set in a curiously bland world, where everybody only listens to classic rock in the radio, all the men wear jeans and plain t-shirts, nobody ever mentions the brand of their car and everybody's favourite movie is Casablanca. This was a real problem with contemporary romances for a while, probably because writers were told not to use any specifics for fear of dating the books. Usually, something dated them anyway, e.g. the heroine desperately looking for a phone booth, a news headline about Cold War peace talks or the heroine wearing clothes that no twenty-five year old ever would have worn either now or whenever the book was written and that even her grandmother would reject as too frumpy.
So if you want to include brand names or pop culture references, knock yourself out. Though you should make sure that the story is still understandable to someone who has never heard of the brand in question. It also helps to remember that if you're writing for a global audience, a brand may mean very different things to different people. Coca Cola can be the symbol of the American dream or of American imperialism, depending on who you ask. What is a luxury brand in one country may not be so in another. For example, I got a good laugh out of the fact that Christian Grey tribes to bribe Anastasia with an Audi in Fifty Shades of Grey, because I'm German and Audi ranks below Mercedes, BMW or Porsche here. So basically, to me that scene said, "Christian Grey, who's supposedly richer than God, can't be bothered to buy a Porsche or a Ferrari or even a Mercedes for the woman he wants to seduce, but instead tries to impress her with the sort of car her parents are probably driving."
