how often do you replace brakes? Is this expensive? and is this a weakness on these cars?
Clean them twice a year and you are all right.
When possible use the high pressure washer in between. Spritz in the direction of the calipers
No the parts are very cheap. Search eBay.
But be warned: when you don’t clean the brakes regularly the rotors will have to be replaced. And those are expensive.
How long do you think the rotors should last? 3-4 years?
That depends on three things.
How much you drive
The level of recuperation when using the brake (OMVS or Powerbox)
How often you disassemble and clean your brakes to prevent dragging.
I learned that, if done correct, you don’t have to part with the rotors under 70.000 - 80.000km.