With the knowledge of ZModelers' tools you already know it doesn't take too much to fix big* mistakes you might have done, when creating the mesh. You can rotate the mesh in 3D View, comparing it with photos.
       You can start with tuning the LAST FILE.
       As for tuning the mesh, it's confusing me how I've made rear door... It will be tuned a bit:

       After you add vertices where it's is shown ( Be accurate and make sure that you have activate correct edge before you use Break tool on it!) - you will find out that you have to Reorient some edges (Break and Reorient tools are the only tools were used to get the following result):

       Hope you will find out the edges to reorient for that result.
       Similar tuning can be done to rear part, but there I've also used welding of vertices.
       Some tuning is also needed in front part:

       ...and on the following image the mesh is just like on the photo:


       Well, it isn't too hard to tune the meshes, increasing level of detail. But good tuning always include reducing polycount. That means that you optimize mesh by removing unnecessary polygons, replacing groups of faces with other faces. For the instance, removing of faces can be done, like on the image:

       After reducing these faces you get something like that:

       Well, this step will be mentioned each time we create new group of faces. Thus after adding new polygons, we tune the mesh. Well, since we all tired of that cars' side, lets go farther and create cars' front.
       The result of tuning mesh in this step is in THIS FILE.