Feeney claimed pole in what was at times a chaotic three-part qualifying on the compact Symmons Plains circuit.
It started with some big names being knocked out in the first segment, before a red flag triggered by a Thomas Randle spin left series leader Brown stranded in 15th.
A fascinating final segment became a three-way shootout between Feeney, Cam Waters and Brodie Kostecki, the former getting the job done with a rapid 50.988s.
That was good enough to leave him eight-hundredths clear of both Waters and Kostecki, who were in turn separated by just five-thousandths of a second.
“We’ve had a fast car today. We were a little bit off yesterday, so to be quick in the wet and convert that to a pole, I’m pretty pumped,” said Feeney.
“Over the whole session I felt really strong, especially under brakes. I had a couple of little mistakes on that lap, I didn’t really know if it was going to be enough.
“It’s tough out there. You’re getting pretty loose into Turn 6, but you’re so deep… I’ve never braked that deep there in my life. I’m having a lot of fun out there.
“It was a shame to see what happened to Will, he got caught out by the red flag. I’ve got to capitalise on these days, I’ll see what we can do this afternoon.”
Nick Percat was fourth fastest ahead of title contender Chaz Mostert, with Cam Hill sixth, Ryan Wood seventh and Anton De Pasquale eighth.
The Top 10 was completed by PremiAir Racing pair Tim Slade and James Golding.
Randle sparked chaos in the closing stages of the second segment when he ran wide at the last corner and slid all the way to the first corner and nudged the wall.
While he did get the Castrol Mustang out of the gravel unaided, he was stuck long enough for race control to call a red flag, which brought the session to an early end.
Among those looking to improve and bank a spot in the final segment was Brown, who will start today’s race from 15th.
“It’s a bit disappointing, we were trending really well,” said Brown. “But that happens, red flags. I didn’t get a lap in at the end, we would have been in the Top 10. But that’s life.”
Randle, meanwhile, was relieved to have not badly damaged his car.
“I’m just glad that the car is one one piece,” he said. “Sorry for the whole team, I was pushing pretty hard. The lap was looking pretty good, probably a top six lap, but you need to cross the line to get the time.
“Just dropped a wheel out of (Turn) 7, which is easy to do. I think Feeney bailed on his lap and then he let Cam through but I was sort of right behind him and understeered off.
“I was praying to the heavens above that I didn’t hit the wall. It was the lightest touch, so the car will be fine, just probably won’t be using that set of tyres again.”
The first segment, meanwhile, claimed Jack Le Brocq (who was third fastest in Friday practice), Grove Racing star Matt Payne and Will Davison, who was dead last and left lamenting not getting any dry running earlier today.
“I don’t really have any thoughts yet, it obviously didn’t go very well,” he said. “We struggled yesterday, we needed that wet practice this morning.
“Simply just out of the window. We tried something with our brakes and I just locked up very run, completely destroyed a left-front tyre. We just made a mess of it.”
Results: NED Whiskey Tasmania SuperSprint Qualifying (Race 17)