Mine will idle up around 1100 if it's seriously cold.
The A6 will run up to about 1500 for a couple minutes, just long enough to scrape the windshield.
I've noticed that with the heater on, the idle is around 800 rpm. turn off the heater and it slows down to about 600. I'd assume the extra rpms are to spin the h20 pump fast enough for heat.