Tandem Solenoid Starter (TSS) motor
WARNING: This page is about a different car, the 2015 Jaguar XF, 2014 Jaguar XF, and 2013 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.
The TSS motor is a unique starter motor specifically for stop/start systems. The TSS motor can control the forward movement of the pinion gear and the rotation of the motor separately, which allows for fast engine restarts, even when the engine is still rotating.