Car Designer Saving Issue

Not sure if this has been asked before, I ran a search but there were too many threads containing my search options that it gave me no search results (lol).
I can only save one car design at a time. If i make a new platform (car) and save it it overwrites the previous save. This occurs even when the revision number is changed.
Is this meant to happen or am i doing something wrong?
This means only one car is ever shown in the sandbox list (unlike the engine list which shows multiple designs)
I can only save one car design at a time. If i make a new platform (car) and save it it overwrites the previous save. This occurs even when the revision number is changed.
Is this meant to happen or am i doing something wrong?
This means only one car is ever shown in the sandbox list (unlike the engine list which shows multiple designs)