There is a process glitch in the early game which can stop all career progression.
When modifying a car in the garage, there is a small 50 credit fee associated with "downgrading" parts.
If, if during first race series, one purchases too many upgrades and exceeds the Road E-Category specification, and does not have enough credits remaining in ones' bank to revert the car into the required race category, career progression seems to becomes completely stuck.
Is there a process workaround, either one which provides a non-career channel for generating credits, or provides a "factory spec" car restore?