It sounds like they went way beyond that. A comment on Jalopnik says:
According to the report from the EPA, it used figures such as steering wheel input, barometric pressure, engine run-time, wheel speed, etc, to determine it was being tested on a dyno.
I think VW is going to be in a world of hurt over this. Apparently their 2016 models are already being held at the port and cannot be delivered to dealers.