There are some authors, James Patterson for one, who love to load their text down with as much detail as possible. In includes specific popular culture or brand references. I’ve never liked this technique. However, there are advantages. The more a reader relates to your story the more they will enjoy it, generally speaking. If they feel like they are in familiar territory, say because the main character wears the same brand of shoes as they do, it helps them become more immersed. I think this is even stronger when the author is talking about locations that the reader knows. This makes the reader feel special; they’re part of a club that knows what’s going on.
With all of these benefits, why is it that I dislike the technique? There are a couple reasons. First, the details are usually things that don’t matter. When a detective is driving across town to integrate a subject it makes no difference if he’s driving a Porsche or a Buick. It may tell me more about the character, does he care about status symbols, but we could find that out rather easily through other methods. Second, adding too many specifics narrows down the choices that my imagination can make. What if my version of a suave spy drives a BMW, when I’m told that he’s driving a Porsche I have to adjust my conception to match. I think that it’s very important to let a reader flesh out characters as much as possible; it helps them see characters they can relate to. Another shortcoming of including a lot of specific details is that those details can change over time. Obviously, you’ll have issues like this all of the time, how many movie and book plots no longer make sense in the days of cell phones, but the author should do as much as possible to limit the damage that can be wrought by time. Going back to the car example, what happens if in fifty years Porshe only makes economy cars (as much as I hope not), while a Buick is the definition luxury. Then, simply be identifying the make of the car, the author has forced an incorrect impression on his reader.
So, in summary, I think that generally – and there are times to ignore every rule – writers should ignore the use of brand names and the like in their texts; it forces too many details onto the reader. The reader should be free to let his imagination fill the details of the scene.