Hybrid drive system and vehicle

A hybrid drive system has an internal combustion engine, electric engine, and transmission having a first spur gear section and a second spur gear section, which provide output via at least one layshaft, and a four-shaft planetary transmission, which has a first planetary gear set having a first sun gear, a first planetary carrier and a first annular gear, and a second planetary gear set having a second sun gear, a second planetary carrier and a second annular gear. The first annular gear is couplable with a crankshaft of the internal combustion engine. The first sun gear is permanently connected to the second annular gear fixed against rotation. A rotor of the electric engine is couplable with the second annular gear fixed against rotation. The first planetary carrier is permanently connected to the second planetary carrier fixed against rotation. A first input shaft of the first spur gear section rotatable around a main axis of rotation is connected to the second planetary carrier fixed against rotation.