New cars are simply better than older ones, model for model. What new cars have that older cars don't is character. Most new cars look the same. They try to copy each other, loosing originality, although this was also done during the 60's.
Cars are no doubt better quality now than they used to be, by a long shot, despite some BS that enthusiasts will tell you. How often did you see sub 2.0 cars reaching 200,000 miles with few issues. Cars use less oil these days, a lot of engine don't consume oil at all. My first car, an Audi A3 1.9TDI had 155k and didn't use a drop of oil, largely this shows there is no wear in the engine, or goes someway to proving that.
Jeremy Clarkson said on a top gear a couple of years ago when he drove a Shelby GT Mustang through southern Europe against Hammond and May in the train, he said that the biggest advance in cars during the last 50 years isn't as much about fuel economy, speed or safety, although they have improved Hughley, the biggest improvement is refinement. You can now take a Fiesta at 70 mph and it is quiet stable and safe. Try doing that to a Cortina and it would rattle and fall apart and the engine would b prematurely worn out especially if you did it regularly.
I don't want to sound biased, but Audi and more recently VW have been using stainless steel nuts bolts and screws in their cars, they pioneered laser seem welding in production cars with the mk1 TT and have used it on all other models ever since.
Recently, during the last 6 or 7 years, car manufacturers have tried to make their cars simpler. During the late 90's and early 2000's, cars were very complicated, and they still are, but using things like electric steering and electric brakes means less moving parts, electric gearboxes now as well are simplifying cars, less moving components and less wear. VW warranty claims in Europe have gone down 45% since 2009, the year in which they used all of this technology.
I am glad to see engines going back to chain cams. There is little excuse for rubber belts, other than for noise with is debatable, but mainly it is cheaper and is a source of income for the dealerships ! But thanks to company cars reps looking to spend as little as possible on there cars maintenance, manufactures have had rethinks.
All in all, I would say cars last longer these days but require more maintenance. It is now more important than ever to have your car serviced when it should be.