It depends on the timeframe. 30-40 years ago there were cars like the Caprice. You can't even get a car with that size and capacity today (look at how small the modern caprice is). I would say the general trend is cars are getting smaller and people are opting for larger types of vehicles like SUVs.
I think you are describing a different phenomenon: Large sedans getting replaced by other vehicle types leaving smaller sedans. The case of the caprice seems to be a totally different vehicle if I am understanding the years you have in mind correctly. Certainly the newer models of caprice are targeting a very different audience than the old ones did.
"I think you are describing a different phenomenon: Large sedans getting replaced by other vehicle types leaving smaller sedans."
Basically, but it's also that the meaning of the terms have changed. The Caprice is and was a full size car. Today's full size car has about the same capacities and room as an older midsize car.
