When modelling a car, it is very important to be able to make "clean" fillets, or creases.

Lets explore a few different ways to make nice "semi" accurate fillets.:

Start this excersize by making a rectangle, delete one of the corner points, and make a fillet on the other corner:


Next lets try to replicate this curvature with a nurms surface, I have found that you easily can get "away" with a 3 point setup on the smallest fillets.
It is not as accurate as using 4 points, but it will not be noticable in most cases:

Side view:

Perspective view:




For bigger fillets it can be nessesary to use more points, thus avoiding visible "edges" after subdivision.
Using 4 pointe also gives you a more accurate fillet.
This can be useful in those situation where you want higher accuracy:

Sideview:

Perspective:


It is important to practice the techniques of this page and the former, because they are essential for modelling a nurms car body..