I tried both and have the 06/07. There is a slight difference in shape and graffix, but thats it. I like the 06/07, it has stripes like a tiger should.
i was told each year new technology/skill out of previous years racing event is built into new racing skills. it would be fun to be able to try out the difference. better still, to tell the difference.
honously i also prefer the 06 graphics.