Internal Clock
WARNING: This page is about a different car, the 2003 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
The internal clock governs when the CPU shall perform a new calculation. The clock has a quartz crystal like those found in wristwatches.
Clock frequencies in a car are much lower than those in a home computer; often approx. 15 MHz.