Mirror an instance over to the other side of the seat. Up to this point you should have something like the picture. In the case of the seats, you don't want to use a symmetry modifier to create the seat on the other side because the two seats will be exactly the same and this is unrealistic. Instead, mirror the geometry to the other side and then adjust the copy by randomly moving vertices so that there are difference between sides. This will add to the realism of the model.
This is what the seats looks like. Notice how the geometry is not perfectly identical because I adjusted the copy. For added realism, move one chair forward a little so that they are not both at exactly the same place on either side.
The seats are located on rails, we are going to create the rails now. We are going to to make them very simple since they won't really be seen up close. Create a long narrow box and do some extrusions to make it look like the picture. That's it! That's all we'll do for the rails. Now just place them under the seats. You can smooth it if you want but it's not necessary.
Now that the seats are done, let's create the strip of rubber that lines the inside of the door. Simply make a box and extrude it around the inside of the door as shown.
There is also a metal strip that runs along the bottom of the door, right next to the rubber. Create a box with 11 length, 4 width and 1 height segment and place it along the bottom edge of the door as shown. You might have to adjust vertices to get it to fit perfectly.