Slug for Model < 3 chars will throw error "Please match the requested format".
Steps to reproduce:
In Makes & Model - section with sample data already installed, select Make "BMW", try to add a new model, fill the data and when saving an error will appear for each slug that has <3 chars like i3,x5,x6 etc
Workaround
Rename all 2 chars slug to 3 chars and Save will work.