The philosophy of durability
How would you define the durability of a car? Intuitively, the simplest definition would be “the length of time that a car functions normally without shutting down”.
However, modern cars consist of components that may have different lifespans, so a single broken part does not mean the overall malfunction. For example, the infotainment system is more likely to break down than the body frame, and replacing the broken one might not cost much money. Another example is the notorious “environmentally-friendly material” used by many brands back in the 1990s that would decompose itself after a certain period of time. It was intentionally designed to “break down” before the whole car shut down, annoying but not devastating. Additionally, regular maintenance, like oil change, is required for the normal functioning of the power components. Therefore, spending money on a car (other than fuel) is unavoidable, and that does not mean a car is not durable.
In my own words, I would say that durability is “the length of time a car functions normally without a large amount of money on overhaul”. So how much is a large amount? I would say that the amount should not exceed the residual value at the time the car breaks down. This is my own explanation to the durability of a car for daily uses.
The logic for designing a race car is much more different than that. Take F1 engines for example. The best durable period of an F1 engine is “one single-race”. Certainly, The engine has to be strong enough to finish a race; however, if the engine can still operate after one race, then it is not light enough. The goal of an F1 engine is to achieve the best efficiency within a single race, so this is not feasible for a streetcar. That is also why some high-performance street car engines derived from F1 have different specifications.
The once famous BMW S85 V10 5.0L engine, which was used by E60 M5 and E63 M6, shared the structure of an F1 at the time, but the actual F1 engine had a V10 3.0L layout with redline over 10,000 rpm. Obviously, the street version V10 5.0L was modified, and the purpose was to meet the durability of a streetcar. Carmakers seldom put the race-car engines directly into a street version. Even the super series of Ferrari, such as Enzo Ferrari and LaFerrari, uses a significantly modified version of the F1 engine.
The sports car whose engine specs are most similar to F1 should be the Mercedes-AMG Project ONE. It has a V6 1.6L turbocharged engine, which is the layout of the current F1, and the engine is only slightly modified to meet regulations. Consequently, this particular engine needs an overhaul every 50,000 km. It is rather a short lifespan under common standard, but Mercedes-AMG believes the idea is feasible because “the owners will not drive this car that much”.
The durability of a car mainly depends on the original design and can be affected by other factors. The maintenance does matter. If the owner regularly maintains the car, it will probably live longer. Additionally, the environmental conditions can be influential. Some places are just harmful to cars. In the southwest coast of Taiwan, cars can often be used for only about 10 years, since the winds contain salts that can erode the body frame. I have seen some discarded vehicles whose engines were totally fine but the rusty holes on the frame were so big.
Similarly, most European cars suffer oil leaks after 10 years in Taiwan, which is mainly due to overheating and the erosion of pipes. According to a friend of mine, who is a mechanic specializing in BMW, the working temperature of European engines is often over 100 °C, while most Japanese engines is mostly between 80 °C to 90 °C. European engines may well survive in Europe, but not the 40°C summers and the rainy winter in Taiwan. V8, diesel, and turbocharged engines are even more vulnerable to that since they generate more heat than small, naturally-aspired engines.
Durability is always an issue when choosing a car. But it is so complicated that no one can determine for sure whether a particular car can last long enough or not. It really depends.