Craig Lowndes believes Triple Eight "still haven't untapped the full potential" of Holden's new-for-2018 ZB Commodore, amid a dominant run for the factory squad.
Led by Red Bull Holden Racing Team pair Shane van Gisbergen and Jamie Whincup, Triple Eight ZBs have won 12 of this year's 24 races, including seven of the last eight.
That run of form has taken van Gisbergen to the championship lead, after Scott McLaughlin's impressive mid-season run in his Shell Ford.
As Triple Eight heads to Bathurst following a sweep of the Sandown podium, Lowndes believes "there's more to come" from the package.
"We still haven’t untapped the full potential of this car," the Autobarn Lowndes Racing driver said.
"Its the first 12 months we’ve had it in operation.
"I think it shows from a lot of the Holden teams that are up the front that it’s obviously a very easy car in the sense of operation window.
"But there’s still a lot of work to be done."
Lowndes' third place in the PIRTEK Enduro Cup opener came at an event he'd classed an 'Achilles' heel' with Steven Richards.
Along with Triple Eight, Erebus Motorsport with two victories for David Reynolds and Walkinshaw Andretti United with one for Scott Pye also have 2018 wins on the board.
Whincup has been impressed by his squad's rate of development, but van Gisbergen says the aero balance of the ZB is key in a "pretty amazing" package.
"The low downforce tracks have really been a struggle in previous years," van Gisbergen said.
"You took wing off the VF and it just wanted to do donuts everywhere.
"That’s one of the first things I learned in racing, balance is more important than grip, and the ZB didn’t make the downforce number outright but the balance of it is so much better.
"Hopefully at Bathurst maybe we can actually take it off max wing - the balance of the car [at Sandown] was awesome and we had straightline [speed].
"The last couple of years we couldn’t have both, so it’s been a really good step forward with the ZB."
Van Gisbergen starts the Supercheap Auto Bathurst 1000 leading McLaughlin by 55 points in the championship.
Whincup and Lowndes are third and fourth, 338 and 567 points behind respectively.