The changeable weather in Melbourne and a lack of pace hampered the Prodrive Racing team at the Sandown 500 on Sunday.
Defending series champion Mark Winterbottom finished 24th to fall to fifth and behind Scott McLaughlin in the overall standings.
"It was a long day," Winterbottom said. "The car wasn't quite there. We need to get our speed back. Yesterday and the day before was pretty ugly.
"To actually get our car in the race then and see Dean [co-driver Dean Canto] doing good sectors was really promising. I was looking forward to getting in but in the Championship we're nowhere now.
"We'll try and win Bathurst, we'll try and win the next ones and push on but we need a quick car. The car's inconsistent. Today it was good and we wasted it but Dean did a really good job. I was really happy with how he went in the car."
Chaz Mostert and Steve Owen were a little more competitive in the Supercheap Auto Falcon.
The pair finished fifth.
"It was a tough day on weather," Mostert explained. "It's pretty hard on all types of drivers being dry then wet then wet then dry and trying to push those limits on a drying track and trying to explore those widths coming into corners and how much you can get out of it so a couple of hairy moments but today our car 55 in the retro livery held up pretty well.
"I think we definitely tuned the car up over the weekend which is pretty hard to do once you roll out of the truck.
"A lot of positives out of today. To be top five, I'm pretty happy and I think we definitely had podium pace. Looking forward to the next event and getting back to Bathurst. My demon/glory track but I'm excited. I'm definitely getting some more consistency with the car, finishing well and qualifying well so I'm pretty happy at this stage. We'll keep working for little gains and see how we roll out at Bathurst."