Cars...ugh. All about perspective, I have studied entire books on perspective and product drawing, and I still can't do it right. So many curves and shapes to keep track of, you REALLY got to have good construction lines for that. I have never been good at it. Takes alot of work! Good luck.
Me too. Which is why I don't draw. Line quality and confidence is important but it all falls apart without good perspective. It's the first thing people notice.
Study perspective - use the box technique. So long as you have a solid understanding of perspective and carefully think through the way the everything should look according to the perspective you set up you should do fine.