The smaller GPS takes into consent the streets. How many lanes does it have? What is the speed limit. I get questions like these at work all day. which one is best either it be the in dash navi or portable. On a constant basis i call the manufacturers to figure how they calculate the routes, and sometime customer service has no clue. SO tech support helps out. This is an issue i have seen, but just like Misfit said "as long it gets you to your destination, why care." Thats why you got it, if you knew the short cuts why use it.