This model started as part of a school assignment in a course I took a couple of years ago, which focused on hard surface modeling. After the course was done, I didn't feel like working on the car again, since I thought it was finished and presentable (and besides, I had so many headaches modeling it that I didn't want to see it again!) Anyway, a year later I decided to re-render it for my portfolio and I discovered a few mistakes, which I fixed. At the time I didn't notice that it still needed much more fixing and I didn't touch it for yet another year. So a few months ago I jumped back into the project and found out how much re-modeling, re-texturing and "re-everything" it needed!
I wanted to make a better render, first using HDRI with backplates and then I wanted to take it further with a studio lighting rendering.
Since the focus of this project was on lighting and rendering, I will leave the modeling part brief. You can find many tutorials on the web about car modeling. I recommend Julian Sarmiento's BMW Z4 tutorial here on 3DTotal if you are using the NURBS approach.
Before starting any project, I collect references about the subject I'm going to work on either for inspiration, or in this case, for accurate modeling (Fig.01). For me, having as many references as possible is very important as a modeler, since the more informed you are the better and easier it is to get the modeling done.
The modeling method used was the one we were taught in class by the great Tom Meade. First, we started with a spline cage (Fig.02), which was then used to create the NURBS patches one by one (Fig.03). The most important part is to have good continuity between the patches, as well as clean topology. Of course, the advantage of using NURBS is that everything is always four-sided.
After that was completed, the patches were converted to polygons for final detailing, like adding extra loops at the edge of each of the panels to keep them tight (Fig.04). Also, most of the smaller details like the rearview mirrors, windshield wipers, tires, etc were done straight in polygons. NURBS is very useful if you are doing nice, curvy surfaces.