Though, bear in mind if you are going into something with designing cars you will find yourself using both: Orthographic for straight-on front, side, top, etc views and perspective for more illustrative angles and ideas. Cars have quite complicated geometry (my dad said some cars can't even be designed on the computer because the technology right now is insufficient for dem curves) and so I recommend drawing basic front, side, top and back orthographics first before you even begin a perspective render.

This one's incomplete, but I would normally make a proper perspective drawing after these three views. You may do a fourth one if it helps you.
With anything, try and draw from reference before drawing from imagination. Try drawing simpler cars with easier geometry like the old Toyota Corollas or maybe a delivery truck.
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