Then you have to look at the lines and shapes of the car.
To get better sight on this, walk around, look at (shiny) cars,
look how the reflections change of shape when you pass by, because of the blends of the car's shape. This gives a better view how reflections are formed.

Then, if you have a design, look at how you have drawn the body lines.
To give an example, if there's an edge in your car's design, this will also have effect on a reflection.

I have searched for a picture which shows what I mean,
take a look at this: [link]
As you see, there is a horizontal reflection of the environment. The BMW has some blends and certain bodyshapes, which make the horizontal reflection change a bit at a few places That's why it is very important to "know" the shape of your design

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Good is not good enough ^^