Eli5: why do many many cars don’t last for a lifetime?
In: Engineering
Like most modern things, if they lasted for ever you wouldn’t need to buy a new one, then companies would go bust because of lack of sales, employment would rise, poverty would increase and we’d have to eat the rich.
Because they are consumer products designed with cost and performance having more priority over durability. As long as the car is “reasonably” durable, which means it lasts long enough to not have the customer sue the maker, while also provides a reasonable demand for service parts for future revenue, it’s fine.
This causes the service costs to eventually go up, while the value of the car goes down. When it no longer makes sense to maintain the car, it’s time for a new one.
Only a few luxury cars survived past that economical end of life, their high purchase costs may have delayed the end of life somehow, but any car lasting very long isn’t because it’s economical, instead it’s because it has historical or sentimental values and the owner kept maintaining it well beyond its economical end of life point.
They’re not engineered to last a lifetime. The longest lasting models are usually overbuilt and not the most efficient and manufacturers can’t squeeze as much profit in both sale and maintenance.
Everything is a tradeoff of quality, cost, size, safety, efficiency, etc. Cars last much longer now than they did a generation ago. But there are limits to how robust you can make certain parts, how much more using metal would cost than plastic, limitations of weather extremes on parts that need to be plastic or rubber, labor costs to locate issues and replace parts. And if you make the engine last longer, you also need to make the buttons on the dash last longer, the seat upholstery more durable, etc so costs multiple across the whole vehicle. To make cars safer, crumple zones make exterior parts more delicate to absorb impact which means higher likelihood of major damage from more minor accidents.
Car makers find the sweet spot of what customers expect for what price. Would customers pay another $10k to get a vehicle that can last another 50k mi? Or are they happy to get 5-8 years from it before they want to move on anyhow?
How would that even be possible? Cars are complicated machines used in rigorous conditions. They get used up. There are design improvements and manufacturing processes become outdated. Nobody in 2023 wants to drive a car with technology that’s 5 decades old, and it would be terrible for the environment.
What is a lifetime? All things break down whether natural or man made. There are cars and trucks with over one million miles on them because they were taken care of and serviced regularly. The average consumer barely does the required maintenance, let alone preventative, and as a result their cars do not last as long. Aside from that the engineers have to balance a lot of factors like safety, comfort and price. Even if you had all the money and knowledge in the world it’s simply not possible to create something that will “last a lifetime” without regular Maintenence and repair. As other replies have mentioned there are also business decisions to be made. Why sell ten cars that last fifty years when you can sell ten cars that need replacing every five years?
There’s a sweet spot where cars are about as durable as the amount of time before a major collision is likely to happen that will total a car. No point making a super durable super expensive car that will last forever if theres a major chance itll get totalled in a crash in the first couple decades
That being said, apart from frame damage, virtually every part of a car can be repaired and replaced, since almost every part is a wear part. You can keep a car going as long as you want if it doesn’t get wrecked, as long as you pay for it.
Anything with heat or movement will degrade over time, it’s an engineering certainty. Over 10,000 miles it will need maintenance, over 100,000 miles it will need several replaced parts several times. Eventually the $ put in per year in repairs will be more than buying a new car that doesn’t have those issues.
No mechanical equipment lasts forever. Parts wear out, things break. Almost all of it is “fixable”, it’s just a matter of spending a lot of money on something that isn’t worth a lot of money.
The materials and processes used to make cars safer in a crash and easier to drive are more susceptible to long-term wear and tear.
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