There are a few things you can do to keep your pizza warm in the car. First, make sure the oven is on. Second, put the pizza on a baking sheet and bake it for about 10 minutes or until it is nice and crispy. Third, put the pizza in a microwave safe dish and microwave it for about 30 seconds or until it is warm. Fourth, put the pizza in a saucepan and heat it up until it is hot. Fifth, put the saucepan over medium heat and cook until it is thickened. Sixth, add the cheese and cook for about 5 minutes or until cheese is melted. Seventh, add the tomato sauce and cook for about 5 minutes or until tomato sauce is hot. Eighth, place your pizza on a plate and top with your favorite toppings.