[Kevan]

I have thought about introducing a new rule where you cannot have the same model as others have already chosen, so we get all different cars   

That would be a nightmare to enforce and would add expense if any of the cars I was experimenting with had already been chosen.
I vote a strong NO to that idea 

I can't say I like the idea either, it's difficult enough deciding on what car in the first place without worrying what everyone else is working on.

Most of us will work on a car without telling the world what it is so how is this is going to work.

No duplicate cars yes, i.e. same livery and number.