I see no reason why anyone should be referencing any kind of brand in the real world. You are given brands of vehicles, company names, beer brands, cigarette brands, etc all created by Rockstar and referenced in the game already. If anything, mixing these brands with real brands would ruin the immersion in my opinion. I do hate it when people reference their vehicles as "BMW" etc. Why? As said above, we already have the brands on top of the fact if you start doing that now nobody knows what to call your vehicle as everyone roleplays them different brands.