Yes, I counted them by hand.
This game will end up with a little over 800 cars so 450 makes it a bit more than half the cars, though there’s a sizable amount with default designs already (FnF, Hoonigan, and all of the race cars).
I wonder if people have experienced the same limit? I’ve seen numbers like 600 thrown around, but it doesn’t seem to be the case. And, unfortunately, saving to current car in the paint booth also saves a copy of the design to the My Designs menu, which counts towards the limit.
A way to get around this is to buy cars from other people, but it doesn’t seem to be a common practice anymore.