Let’s take, for example, my old E36 M3. It featured a US-only spec 3.2 liter straight six cylinder engine that produced around 240 horsepower. It also had a unique problem in which the nut that held the sprocket driving the oil pump would fall off. Yes, the one thing that made sure your engine was oiled properly would simply fall apart, because it wasn’t torqued down properly from the factory.
If this part went, as it was apt to do over time, your engine, maligned by some as the worst M3 engine ever made, would be considered a prime candidate for the deadest M3 engine ever made, as the insides would turn themselves to confetti in short order. This wasn’t so much as a defect as it was a promise, a race against the clock that would net you one hell of a story to tell your friends as you cry into your already tear-soaked repair bill.
And that’s the reliable one.
If you move to more late model stuff, the situation gets a bit more dire. Let’s take the E46 M3, for example. It featured a 333-horsepower naturally aspirated inline six cylinder engine that was more unreliable than an AA meeting sponsored by Miller Lite. These engines were were plagued with connecting rod bearing failures, issues with the variable cam timing (VANOS), crankcase ventilation failures, hard starting, and their cooling systems were made of plastic and sealed, ensuring catastrophic failure where scalding hot coolant would shoot out of your engine bay, overheating your engine, at which point your head gasket would blow.
