Modelling the guide mesh of a car

I struggled so many times in modelling a decent car in blender because I am still a beginner. I Googled a lot of car modelling tutorials but they did not seem to work out for me. One time, I found a website like this: However, the tutorial series will require me to pay 45$ to gain access to it. On the website again on the other hand, I found a GIF image about the guide mesh which served as a clue to how should I model my car properly but one problem, the guide mesh is made for the Corvette C7. Therefore, I tried searching in YouTube about this but it shows tutorials for modelling character base meshes. Will anyone help me how do I model the guide mesh of any car like the Chevrolet El Camino SS, Nissan GT-R or any other car?

This is one of my car blueprints:

And another one if you want to:

What is a “guide mesh”?

Like this. It is used as a reference to modelling the details of the car.