There's a good chance he is for the second car, and you'd both be co-owners of the first car as you both paid some money.
Under the QLD Transport Operations (Road Use Management—Vehicle Registration) Regulation 2010 I suspect you will just be considered the registered operator.
However, while he has paid for the cars, was there ever any agreement between the two of you regards 'legal ownership'? And if your partner is your husband/defacto, in a split up, the cars are part of a joint asset pool.