I have a friend who has a Ford Escape hybrid that has a 120 volt outlet in the car. When our band has a carry-in, he plugs in a crock pot with his specialty, scalloped potatoes, and we make the 15 mile trip. However, I don’t think the crock pot draws as much power as a coffee maker.
However, engines do generate heat and much of it is wasted. Maybe you could adapt the cooling system of the car to make the coffee. There should be a way to add coffee to the water in the radiator and keep it hot while driving. For winter freeze protection, you could add enough whiskey and have Irish coffee.