Yes. Fan Pack drivers will come with an already upgraded car. However, you can further upgrade Fan Pack cars just as you can update your career car. However, your R&D Center must be leveled up so that you have car parts available that match what your Fan Pack car needs.
For example, if your Fan Pack car has an engine at Level 7, your R&D Center must be at least Level 8 to research a Level 8 engine that will install on your car.