Depends. If you're trying to draw a specific car or at least a brand, you need a shit ton of reference photos of that car. If you're trying to draw a car that doesn't exist irl, but could exist, you need an even larger shit ton of reference photos of the general kind of car you're trying to draw
Its a lot easier if you have a good understanding of cars and understand what role any given part serves and how its typically attached to the res of the car
Comments
I find hard surface really difficult to draw, but I love 3D modeling it