Also they know more about how to design a cylinder block so the cylinder walls won't warp out of round as bad as they sometimes did in the old days. All that means less vibration, and less vibration means less wear. All the good cars now have thermostats to control the water temperature. The motor heats up quicker and even a careless driver can't run 'em much too cold in winter. There's less crank case dilution to spoil the oil's lubricating qualities and the oil filters they're fitting keep the 0il clean.
Air cleaners keep dust out of the cylinders, and that cuts down the carbon quite a bit.
Higher compression means better economy. As for looks, the modern lacquer finishes stand up three times as long as the old paint finish, and the chromium plating on the bright parts stays bright without polishing. I thought all that stuff was just talking points. They look pretty light and tinny to me. I think the bodies they're fitting now are remarkable considering the price.