> most modern hybrids use the ICE at higher speeds for efficiency, right? What does that mean in terms of added complexity and reliability?
A typical ICE is most efficient when running at moderate load and somewhere between 1800 and 3000 RPM. That's what happens naturally at highway speeds, which is why traditional ICE cars get better MPG on the highway than in the city, and why hybrids run the engine on the highway.
Hybrids gain a large advantage in stop and go traffic because then they can recover energy through regenerative braking and contribute it back when accelerating, which allows the ICE to either run within its peak efficiency range or not run at all.
So on the highway a hybrid is basically doing the same thing as a normal car. It might eek out a little more efficiency by using electric boost when going up hill and regen when going down hill to keep the engine load more consistent, but it's nearly the same. But highway miles are what put the least amount of wear on a car.
It's stop and go traffic that causes the most wear because then you're putting high loads on the engine during acceleration (and using lower gears which require more engine revolutions per distance traveled) and burning through brake pads during deceleration. Which is the thing hybrids avoid doing by using the electric motor.
> But the alternator vs electric motor aspect misses the original point about cost, considering the motor may cost 8x-10x to replace.
When alternators or starter motors go bad it's commonly the components like brushes in DC alternator/generators or the clutch pulley or solenoid that hybrid motors don't have to begin with because hybrids typically use AC motors permanently connected to the drive shaft. AC motors are extremely reliable and will typically outlast the rest of the vehicle.