Geoghegan won the Round 4 opener of Toyota GAZOO Racing Australia GR Cup, ahead of pole sitter Hayden Hume with Ben Gomersall third.
The round started badly for Hillyer with only qualifying 19th and was further thwarted by a five-grid penalty for impeding. His race lasted a little over a lap when he slowed and stopped on Mountain Straight.
“The engine just cut out and we don’t what the problem is, but it is definitely engine,” said the Walkinshaw Andretti United junior development driver.
Despite his non-finish, Hillyer maintained the points lead, albeit significantly reduced, over Owen and Geoghegan.
Hume won the start and led the 35-car field to the top of the mount for the first time. Geoghegan slotted into second from his third place on the grid. Sixteen-year-old Lincoln Taylor sat third ahead of Ben Gomersall, James Lodge, Lachlan Gibbons and Owen.
Geoghegan tailed Hume down Conrod Straight and slipped passed him at the Chase left hander. From there Geoghegan was able to edge away to a 1.3s lead as Hume held off Taylor and Gomersall.
Hume was able to break free as Lodge passed Taylor and Gomersall. Hume closed on Geoghegan but not enough to obtain a slipstream gain as Geoghegan was particularly strong from Skyline to Forrest Elbow.
Lodge lost his spot to Gomersall to on the penultimate lap as Taylor placed sixth in front of Gibbons, Owen, Ryan Tomsett, Josh Anderson and Clay Richards in 10th.
The Toyota guest drivers were last year’s series winner Ryan Cash, New Zealand’s Hunter Robb and Royce Lyne. They finished 12th, 15th and 16th.
There will be a second GR Cup race on Saturday before the third on Sunday morning.