Some areas of newer cars are more reliable but others are not. Older cars HVAC systems were cable (my favorite) or vacuum operated. Pretty easy to fix and service, generally without too much disassembly. Todays junk has a gazillion actuators to crap out and just replacing one of them generally calls for an entire dash removal. When all of the cost are added up including labor, the price can easily exceed the worth of the vehicle several times over. This doesn't include the very complex, finicky and expensive all in one infotainment center that controls radio/HVAC/Navigation, ect. Fixing/replacing these is very involved and expensive. All in one means when one area fails, the entire unit needs to be replaced. Most of these are a dealer item only, not available aftermarket. After 10-15 years, you're up a creek if it fails. There are some out there making a business repairing them but it's only a matter of time when that can no longer be accomplished without the necessary parts.
These bazillion gear automatic transmissions are causing a lot of issues, especially in American vehicles. It has gotten so bad that American manufactures are sourcing Aisin transmissions from Toyota 'cause they can't figure out how to properly build one. To make matters worse, the fluid is claimed to be sealed for the life of the transmissions which is BS. More gears = more shifting = more wear and tear on the fluid and the need to change it out more regularly. Some of these transmissions are serviceable but it's a VERY involved process. Dipsticks have all disappeared for almost a decade now. Toyota is about the only manufacture that can make a reliable and durable CVT. Honda automatics have always been weak (like all Chryslers with an overdrive auto) but the trick is to drive them easy and change the fluid every 20K miles. Pretty hard to accomplish that in models that don't contain a dipstick.
It is me or has anybody noticed the shear amount of LED lights that fail on newer cars? The first and only light bulb to fail on my Honda Accord was the one of headlights, after 17 years running them at least 6 days a week, generally twice a day during the winter months. The rest of the bulbs are still original at 25 years old and work fine. So much for LED's being more reliable. Look at the price and labor to replace LED lights, some can get close to the 5 figure mark and access is very involved.
Yes, some of the older vehicles went through alternators more often but they were easily accessible. Also, the alternator didn't have to be replaced because the internal voltage regulator died. Older generators are a cinch to repair, just brushes and sometimes bearings. Modern stop/start vehicles eat through starters like crazy in town driving situations. Ever replace a starter on a Cadillac NorthStar or other V8 equipped vehicles where it's located under the intake manifold? That has to be the dumbest place to put one and even Toyota is guilty of this.
My buddy had to have his entire dash cluster replaced on his 2003 Chevy truck when it was 2 years old. Coworker had the same thing on his 2008 Chevy SUV (forget what it was now) as the gauges started becoming inop. Dash cluster on my Toyota truck is about to turn 40, no problems. Honda is about to turn 25, no problems. Haven't had to replace one single dash lights anywhere on either vehicle yet. Never had to fool around with gauges on my really old stuff from the 50's-70's, they're simple and just worked.
In tank fuel pumps, yeah, those are always fun to replace. I'd rather replace a mechanical fuel pump on the block like the good old days. 2-3 bolts and a couple of easy removable fuel lines and the job is done in 15 minutes on the side of the road.
Anything with cylinder deactivation has been shown to rapidly increase piston ring and cylinder wear/tear.
Water pumps driven by a timing chain are very expensive and involved for replacement. Another stupid design.
This small engine/turbo combo nonsense is quickly wearing out engines. It's also wearing out the turbo's. Expensive to service/fix.
Light tension piston rings wearing out quickly and burning oil, still a problem 15 years later.
I agree with Sean, the mid to late 90's through the early 2000's were prime years, especially for the Japanese. Just enough tech to run everything efficiently and easily access OBII computer diagnostics in real time but without all of the unnecessary complicated BS like the last 15-ish years.
I was chatting it up with a Toyota tech last year and I was telling him how my folks 2001 Toyota Camry has over 300K miles with nothing done except a driver side window regulator and drivers side door handle, besides regular scheduled maintenance. He said a new Camry is waaaaay too complex and won't last that long, at least not without a decent amount of repairs. I believe him.