Progression Between Online and Single Player

I understand that these are meant to be 2 different game modes within the same game, however, if I have grinded to get a car to my exact liking in single player, I expect to be able to use that car with my friends in online. It is a sore loss that this game misses such a detail that enhances the user experience. Instead, the current system artificially doubles the user engagement time by requiring us to upgrade the same car multiple times. And we WILL want to do this because if we use a car in the single player, there's a very good chance we're fond enough to use it online. Instead this just makes playing both modes seem like a chore so we tend to stick to just one. This system is more poor than the multiplayer in Most Wanted 2012.