Whincup making his second pitstop one lap before Reynolds, and passing the Penrite Holden on its outlap, ultimately made the difference.
"We were battling hard for the first two stints," Reynolds said.
"I think his car was a little bit better than mine, he could just put a bit more pressure on me here and there, and I didn't have an answer for him, I couldn't drive away.
"He undercut me which is a good thing; what I should've done is pitted when he pitted, or the lap before even, just to sort of negate that.
"What really screwed me over was on my in-lap two blokes fired out of pitlane and started battling on cold tyres and that probably cost me half-a-second, which was probably enough to get the job done."