Gran Turismo creator Kazunori Yamauchi has told our sister site Eurogamer.net that Gran Turismo 4 for the PlayStation Portable is unlikely to be finished in time for a release this year.
The game was originally announced back in 2004 and due for a release in the spring of 2005 in Japan, but has since met with multiple delays.
"We had been developing the PSP version, but the problem was that the PS3 version took much more time and effort than we had first imagined," revealed Yamauchi.
"So that's been delayed - I don't think we'll be able to make the end of this year for the PSP version, but we are working on it," he said.
He also said that over the four year's of development, the PSP version of the game has undergone design changes, with online features in the PlayStation 3 version of the game likely to influence the forthcoming handheld title.
"Once we experienced PS3 online and went through all of that, we came to the conclusion that PSP should not be a standalone product - it should be linked in to the world of Gran Turismo, linked with the PlayStation 3," said Yamauchi.
As one of the titles synonymous with the PlayStation brand, Polyphony Digital's Gran Turismo series has shipped over 48 million units worldwide since first appearing on the original PlayStation.
The series is so well regarded in the automotive industry that Yamauchi has even been invited by Nissan to help design the multifunction display for its supercar, the GT-R.
This week Gran Turismo 5: Prologue - a cut down version of the full GT5 game expected next year - entered the UK charts at number one, becoming the fastest-selling PlayStation 3 title within a week.