When someone tries to figure out which cars they are missing. I always tend to suggest going into Horizon Promo and searching the not owned category. As you may have sold a hard to find car in the past without realizing it. Which does not automatically disappear from the car collection tab.
I think for future titles or possibly this title it would make more sense if the traffic cars and other impossible to obtain cars do not show up in the not owned category. It can be confusing for new players as nobody can own them. Yet seeing them there may make you have second thoughts.
Having them in the promo isnt a bad thing. I actually think its kind of cool but may leave it in the captured/not captured category. Sorta like the Owens P1 in Horizon 4. It had the same situation when reality was it could only be owned by one person… And was later removed from the owned/not owned category.