Denniss, while I'm not inclined to take wiki info at first glance, I think it's probably taking A-5/U3s into count, so in that respect it's a plausible number. I guess I was reading about factory-designated F-models rather than designations given after the fact, but I guess we're on the same page.
Wmaker: /R4 is attributed to a GM-1 kit by some sources, and attributed to a package relating to the MG151/20s in other sources. Outside of a few test charts and calculated speed curves, GM-1 wasn't really used in 190As. They didn't have much of it, and even though it was available earlier in the war it was limited to special models which explicitly state they use GM-1.
I don't doubt the author you stated put that into his book. I doubt that it signifies what you think it signifies. Even assuming it refers to a GM-1 setup, that doesn't change anything, either. The aux tank in the 190A-8 was included from the factory to use MW50 or GM-1. That doesn't mean they used MW50. Instead they used that tank for other liquids. Primarily C3 injection. It also doesn't mean that these airframes were ever used. Or perhaps they were the production numbers for the various test frames upon which the GM-1 testing was based.