The Nissan Altima will run an updated aero package for the remainder of the 2019 Supercars season.
Kelly Racing, which now runs without official Nissan support, has struggled during the current campaign and Nissan is the only brand yet to win a race in 2019.
The team has now successfully lobbied to update the Altima's aero after presenting CFD analysis, which was validated during a non-testing track activity known as a 'ride day', to the Supercars Commission.
The proposed changes have now been approved, and the four Kelly Racing Altimas are set to run a shorter front undertray and a higher Gurney flap on the rear wing in a bid to shift the aero balance to the rear.
"We're pretty happy with what we've been able to do to the car," said Kelly Racing team owner Todd Kelly.
"We're not expecting to jump up 10 spots on the grid, but it'll certainly be a little bit better than what we've had and, more importantly, a little bit more tuneable."
Supercars's head of motorsport Adrian Burgess added: "Kelly Racing asked for more time before making an adjustment and obviously we want them to make a positive adjustment.
"It hopefully offers more of a workable platform for the drivers and engineers, opening up the set-up window."
The updated aero package is the second aerodynamic change to the Altima this season after the car underwent re-homologation at the end of last year.
It also follows aero adjustments to the Ford Mustang and the Holden Commodore, amid an ongoing search for parity sparked by Ford's new-for-2019 racer.
The Mustang has won 17 of the 20 races to date compared to Holden's three victories.