No! You cannot use your DoorDash card to pay for gas. To understand this better, you must know the purpose of the DoorDash credit card.
Customers make orders from their DoorDash app and pay using their credit or debit cards. Their food orders will appear in your driver app, and you can choose to deliver the order.
When you choose to deliver, you will go to the merchant to purchase the food. Your DoorDash card is funded after you accept the food request. You then pay for the food with your DoorDash card.
This means your DoorDash card only contains funds when you have a food order to deliver.