You should really stick to a single project per thread, it makes topic search more effective when looking at thread names.
About your 2D sketch, you should first try to produce a 3D cage of your model. Here's an example of what I mean :
The model shown in this picture is a standard mesh, but without any faces. Just edges with enough vertices to make them looking smooth enough.
Achieving such a model is a good first step toward 3D modeling, as it will get you thinking 3D about every single shape of your car.