Actually by definition, no one in the race was a ringer:

4. U.S. a contestant, esp a horse, entered in a competition under false representations of identity, record, or ability

But in the context of nascar and the way ringers are defined Ambrose is not a ringer, he's a full-tiime driver in the series and has been for years.

The other 'ringers'-they aren't in top line rides, no chance of winning so i don't see the point of bringing them in.