You will definately need to be there for 12 months and own the car for 12 months and provide proof of purchase and log books of running expenses for the 12 months plus be able to ducument your time spent there. Also all of this stuff must be lodged prior to the car landing on Australian shores otherwise the car will be turned away or you will only be able to race/rally reg it. Have a look at the dotars site. I think it is www.dotars.gov.au.