What I'd like to see is a greater sense of car ownership as an extension to car collecting. Make the Forzavista space(s) feel like an actual working space where you in one spot can browse ledgers with one keeping track of the whole car collection and another showing history for the chosen car, chronologically listing things like entered events, mileage, modifications (and how they affect performance), tuning adjustments (and how they affect dynamics), purchased upgrades, milestones, maintenance, etc. Think similar to the dynamic progression diaries seen in games like Uncharted 4 and RDR2. Then another spot could have a laptop where you can access stuff like dealerships, auctions and leaderboards.
It's basically a question of changing the presentation around existing mechanics to the point where players feel immersed in an interactive universe around their cars. The benefit of such an approach is that it can be done without having to reduce the car count, unlike an approach that would focus more on celebrating every car in greater depth. Essentially I'm talking about making a glorified version of the existing menu icons and screens that is more alive and integrated in Forzavista.