What if cars grew from use - like animals. A lot of people with big/small vehicles today would be flipped around.
Just thinking about all the... Shall we say "under used" pickup trucks in my neck of the woods. Bought to look like the owner moves shit - when in reality it just signals to me they have the money to make others do it for them.
And then there's those of us who stick 8-foot boards diagonally through their Honda Civics so a couple inches are sticking out the front passenger and rear driver windows.
Coincidentally, by far the most use my dad's pickup truck bed gets is when I borrow it from him to really load up at Home Depot.
It depends, I get a lot of use out of my SUV hauling around some bulky junk- lumber from home Depot, camping gear, kayaks, occasionally towing small trailers, etc. So being able to buy smaller cheaper cars and grow them into what I need could be pretty sweet.
But I'd worry about them overgrowing, I've driven bigger trucks, they're not for me. Mid sized SUVs and compact/mid-sized trucks are about the sweet spot.