Shia LaBeouf doesn't piss his money away on fancy cars -- he pisses it away on fancy, old cars.

Sources tell TMZ that Shia LaBeouf recently took a train to San Diego and bought a bright red 1975 Checker Marathon -- the same type of car used as a taxi back in the day. No, it doesn't transform into a giant ass kicking robot.

During his Disney days, Shia was driven around in a Checker by his manager.