With my A6, there was a log book of 40,000 miles worth of services with the local Audi dealer. When that ended, there were other random services. But certain things, like the timing belt replacement weren’t reported on the Carfax. Why is this? Do some places just not report events to the Carfax reports or something?

The car came with a total of around 30 service records and some general maintenance items that were signed off and stamped by the Audi dealer int he book intended for maintenance.