Phillips beat out contestant Jessica Sanchez earlier this week, winning a record deal and a $300,000 (£190,000) advance on completion of his first album.
Phillips was given the brand new 2013 Ford Fusion as a gift during the American Idol grand final last week, but sources told TMZ that the 21-year-old musician has refused to give up his own 2001 Ford Ranger truck.
Phillips suffered from health problems during his time on American Idol, and underwent a total of eight operations while competing on the show.
He is scheduled to undergo another kidney surgery later this week.
It was recently revealed that Sanchez will be the first Idol runner-up to receive no album deal after the show.