James Moffat admits claims his car was running on so-called "jungle juice" have taken the gloss off his maiden V8 Supercars victory and Nissan's first in 21 years.
But the son of racing legend Allan Moffat insists he is proud of what was a dream finish in Saturday's opening 60/60 super sprint race at Winton.
The 29-year-old crossed the line ahead of his Nissan teammate Michael Caruso, marking an historic one-two for the manufacturer who only returned to the series this season having left in 1992.
The success followed the pairs' impressive performance in qualifying and practice, benefitting from testing sessions at the track last week.
However, championship leader Jamie Whincup questioned whether the two Altimas had been given a boost by a new fuel blend being tested during this weekend's round of three races.
Both cars, as well as one of Erebus' Mercedes, were running on a slightly lower ethanol ratio in a bid to improve fuel consumption.
All team owners and the V8 Supercars commission had agreed to the test prior to the race.
While V8 Supercar engineers insist the fuel offered no power or performance advantage, having analysed the data post-race, Whincup took exception.
"The Nissans were quick. Obviously they've got very good aerodynamics, we've known that," said Whincup, who was forced out of the race while leading the pack 10 laps into the 40-lap race because of gearbox issues.
"They've got some jungle juice in the car now which has given them a bit of a leg up."
Ford driver David Reynolds also raised his suspicions on Twitter.
"Heard there was peptides in the fuel? #ASADA #V8SC", he posted.
Moffat denied the fuel provided any benefit, saying the slow and tight circuit suited the Nissans which lack the horsepower of Ford and Holden.
"It has no performance implications on the car at all," he said.
"It is purely for fuel consumption.
"I'd take the 20 years of engine development the Ford and Holden guys have on us any day of the week."
Asked whether Whincup's suggestion had affected his feelings about the win, Moffat said it left him annoyed because of its potential impact on his team.
"They've worked their backsides off to get us to this stage," he said.
"It's taken a bit of gloss off what's been a pretty good day.
"One-two at this level of motor racing is nothing to be sneezed at.
"People can call it jungle juice or whatever they want, but I think Jamie's had a pretty good run over the years."
All cars will return to fuel normally used for Sunday's two 100km races - a move that Holden's third-place getter Jason Bright welcomed.
"This place was certainly going to suit them. Whether the fuel's making a difference at the moment, I'm not an engine builder and I don't think anyone's had enough time to see whether it does make a difference," he said.
"If they win tomorrow, case in point: no one's going to be able to complain about it."
