Too bad nothing nowadays is meant to run more than 5 years.

Where do people keep getting this from? Cars today tend to last far longer anywhere where winter is a thing.

As for air cooled vs water cooled engines, the power output (and vehicle mass) has to be part of that conversation. Yes air cooling works on on a 25 HP motor, but it doesn't work so well on modern engines making an order of magnitude more power.

You have clearly never lived with an old air cooled VW engine and dealt with it overheating in traffic.

If you genuinely think that those old engines are still running on original parts. Then I don't know what to say, because you wouldn't understand any of it.

Air cooling is a lot less complex than water cooling, so there are fewer points of failure. If both can do the job, I'll pick reliability over efficiency every time.

Air cooling is not as effective as water cooling,

It's not that simple because air cooling in pcs today means a heatpipe. A heatpipe uses fluid (such as water under a vacuum) that boils at a low temperature. The phase transition of liquid to vapor transfers hundreds of more times heat than simple conduction of cold water running over the CPU.

https://en.m.wikipedia.org/wiki/Enthalpy_of_vaporization

It's how refrigerator compressors work to cool things so effectively. The genius of a heat pipe is it works without an electric compressor ( this limits it's cooling ability but it's still genius).

So a heatpipe CPU air cooler with a 120mm radiator will outperform a water-cooler with a 120mm radiator in almost every situation. The advantage of water-cooling is you can make that radiator huge (280mm is typical today), and place it on one of the side/top panels of the case where air is cool instead of deep inside where the air is hot.

Yeah but VW engines were pretty small, carrying pretty small cars.

Similarly it's actually easier to fuck up the design of a water cooler than an air cooling system. Notably motherboard warp can happen from an improperly set up water cooling.

Cars built today will outlast most of the old Beetles. There is a big survivorship bias at work. A percentage of them were built to slightly tighter tolerances and quality than all the others off the same line. A percentage of those will end up in the hands of owners that are meticulous about maintenance, never get in a major accident, and keep it going for decades. The handful you see left are the ones that went through several rounds of small percentage chances. There were a bajillion of those old Beetles made, so a few were bound to get through.

What cars have problems with today are things that rarely have to do with making the wheels go. They get into accidents. Their auto-dimming back windows no longer work. The GPS doesn't get updates and thinks you're three counties away. The engine and transmission, however, will probably go to the junkyard in perfect working order, even with shitty maintenance on the part of the owner.