Treasurer Wayne Swan has defended Prime Minister Kevin Rudd's acceptance of a free vehicle from a Queensland car dealer.
Ipswich dealer John Grant said he gave Mr Rudd a 1996 Mazda Bravo ute as a "gift" in 2007 and received no benefit from it.
Mr Rudd declared the ute on a register of pecuniary interests two years ago.
The coalition wants to know if the prime minister's office has since made representations on Mr Grant's behalf to Treasury about a scheme known as OzCar, which provides money to dealers who have been left without finance because of the global economic crisis.
Opposition treasury spokesman Joe Hockey told Network Nine there are "many unanswered questions" that need to be put to Treasury officials.
Mr Hockey also questioned why Mr Rudd accepted the ute in the first place.