The US producers of Gran Turismo PSP have said there are no plans to release any downloadable content for the game.
A reply to a question on the PlayStation blog reads, "We're planning on having 800+ cars right out of the box, which is pretty much a lifetimes worth of racing (Im still unlocking cars from GT4)."
The producers went on, "With that sort of breadth and reach of options, having DLC would be like tossing water into the ocean." That's like ******* in the sea, for our UK readers.
As announced at E3, Gran Turismo PSP will launch alongside the PSP on 1st October.