You can keep leveling up, but you won’t really see any benefits to it until you connect online.
You want to play together with your friends need Speed Payback, you need to have both the game. This adds a bit of a combat element that would’ve been enjoyable- except for, you guessed it- the cut scenes. You can then play both online and offline together.
What need for speed is split-screen in carbon nfs when you choose gamemode you will see screen option divided.