'Idol' Winner Phillip Phillips -- Celebrates His Win with a ... $25k SURPRISE!

"American Idol" champ Phillip Phillips is celebrating his win by PARTYING LIKE A ROCK STAR IN VEGAS ... at least that's what he should be doing, but instead he's hanging out with his parents and giving them his brand new car!

Sources tell TMZ ... the brand new 2013 Ford Fusion (valued at $25,000) Phillip was given for winning the competition will actually be a gift to his parents ... because he's perfectly happy driving his 2001 Ford Ranger truck (see below) and refuses to give it up.

In fact, we're told Phillip wasn't even tempted to use the new car for himself.