I remember hearing stories about dealerships papering their glass windows when the new models came in each year so that no one could see the new cars until the official unveiling. Every year there was a significant model change, as you say, solvegas, although in Europe, that didn't really apply.
However, what strikes me most about going back and looking at old cars prior to the 1970s is that each car company (or marque, may be a better word) basically ONLY SOLD ONE CAR. Sure, they're were different models, but to my eyes, one 1955 Buick model looked pretty much the same as all of the others. Can I tell one model of say, a 1938 Studebaker from another?

Not me! There were different chassis and motors and body shells varied slightly to accommodate the different chassis, but aside from the 'Vette, all the other 1957 Chevys look the same to me (even the station wagons kept the same look in the front). As the 60s and 70s rolled around and manufacturers began introducing really different models to compete, like the Mustang & Falcon or Chevy II, their costs were probably a lot more. Look at Chevrolet's line-up today: Spark, Sonic, Cruze, Volt, Malibu, Impala, Camaro & Covette & the truck lines! There's no way they could substantially change
each model
every year and remain afloat.
Personally, I feel that car design has woken up a bit in the past decade or two. The cars from the 80s were generic boxes with no character. Some interesting lines began to get reintroduced in the 90s, but I think a lot of cars have quite a bit of character today compared to those decades. That character pales next to cars of the 50 & 60s, but I think there's some nice design flair going on these days. Just look at the new Ford Fusion, new Mazda 6, Dodge Charger or Cadillac ATS. Cars from the 80s just put me to **82**.
Oh, and to my eyes, cars from the 20s, 30s & 40s all look the same for any given year. Just thought I'd mention it.
