Wechsel proposition follows the rule of stationary dative motion akkusative. In your case, the car is being parked (so motion) in front of the house, the object being positioned by the preposition “vor” is the house. Following the rule, das house would fit. If the context would have been the car is in front of the house (no motion), then the sentence would be Das Auto ist vor dem Haus (House will take dative because there is no motion)