No, you are the one missing the point.
What is the most plain definition of expansion? More maps.
When the previously mentioned Oblivion got an expansion, what did it have? More maps. When Xwing got an expansion, it got more missions.
An expansion is when you use the same gameplay to do the same thing with a different story in different places.
In other words, just adding new cars (graphics) and locations, and even just driving type missions, which they've had since GTA3, IS an expansion.
You have more ground with the talk of stat leveling.