Arnold Schwarzenegger dropped a ton of cash on baby mama Mildred Patricia Baena, but not enough to cover her car payments -- because TMZ has learned she defaulted on her ride back in 2004.
According to documents filed back in 2005, Baena had her car repo'd in April 2004 after she failed to make payments on a 2001 Nissan Frontier.
We're told a collection agency still has an active case on Baena for $17,193.82 in back payments.
As we previously reported, Arnold forked over the down payment on Baena's home in Bakersfield, CA and even picked up the tab on her niece's Quinceanera.
Think he'll open the checkbook again?