Operation Burnout forum member, supercarFTW! has pointed out that the Japanese version of the Burnout Paradise demo features a different car. The Nakamura Ikusa GT features in the Japanese demo as opposed to the Hunter Calvary in the US and European versions.
Anyone with a Japanese Playstation Network account can download the demo for free to try out the car themselves.
UPDATE: Confirmed that the Japanese 360 version of the demo also features the different car.