Game director Paul Rustchynsky offers up an explanation of how this isn't merely a demo.
The PlayStation Plus Edition hasn’t changed. It’s hardly a demo because you get access to all of the game’s features online and offline. The difference is that you only have 10 cars and you can only race in one country (which gives you access to 5 tracks with 11 distinct variants).
The PS+ version of Driveclub will release alongside the full retail version on October 8, 2014.