The official Scalextric game app from Sabec has been proving popular since its release late last year.
The app became the number one selling racing game on iPhone in the UK after its launch in December - and is still in the top three - number seven in the iPhone arcade game chart and the number 17 iPhone game overall in the UK.
The lite version has also reached half a million downloads.
With customer demand still high, an iPhone update is due shortly, while a version of the game is also being developed for the Google Android mobile phone operating system.
"Sabec have done a great job in taking the excitement of the home track to the new and wildly successful world of the smartphone app," said Charlie Donaldson, joint MD at Rocket. "The game's success underlines the strength of Scalextric both as a leading game and as an instantly recognisable brand.
"We're looking forward to continued success with both the update and the Android platform version."