Thanks for the help!
After contacting BMW about 5 times, they shared some specifications:
Brand: Valeo
Voltage: 250V
Cont. power DC: 23.300W (at 330V and 4.800rpm)
Efficiency: 94%
Diameter: 300mm
Length: 115mm
Mass: 26kg
Unfortunately, this is not a standard generator that can be bought.
Since...