It does seem to be the case.
The only explanation I can come up with is that, the dimples 'DO' act as some form of VG, creating a lower local pressure along the 'boundary'.
With respect to the Mythbusters Ford sedan, they were able to induce the turbulent boundary layer to remain attached a bit better, minimizing the existing separation bubble, allowing enhanced flow reattachment, with higher pressure at the inevitable separation line.
Base pressure was slightly increased.
Pressure drag decreased.
Total drag reduced.
