Abstract: A starter—generator system for motor vehicles permits implementation of various starting methods including direct start and impulse start. The system also facilitates additional operating modes, including generator operation and/or recuperation operation. The starter-generator system electric machine which can be used as the starter and the generator is to be connected by way of a planetary drive with a shaft train situated between an internal-combustion engine and a transmission, the planetary drive being at least partially usable as a centrifugal mass for impulse starting operations.