Hide everything except the car doors and the rear engine door. Now just like you did with the rear lights you need to detach the polys shown below and shift+drag them out in the positive x-direction in the side viewport. Make them a new object and name them something like "Rear Door Handle".
This is a chance for you to practice the polymodeling skills you have learned so far. See if you can go from those two polys to the door handle shown below. All it takes is some cuts, welds and extrudes. It's not very hard and by this stage it should be no problem for you. After about 10 minutes or so, you should have something resembling this:
Now onto the handles for the passenger doors. Create a small box in the side viewport in line with where the door handle should be. Give it 1 length seg, 1 width seg and 2 height segs. Select the poly shown below and extrude it out a few times also beveling it to create the curve of the door handle. After some extrusions and bevels and tweaks you should have this:
Now add details by chamfering or cutting edges etc. How much detail you put into it depends on how close you are going to get the camera to the car when you render it. If you are going to be doing extreme closeups, then it's better to put as much detail into it as possible but that will cost you polys and make your model very heavy on your computer.
Next you need to add the indentation in the door under the door handle. This should be easy if you use a boolean. Create a sphere and squash it into a oval shape. Now position it in the door with half of it intersecting with the door. Select the door and then click on the "Compounds" tab on the tool bar. Now click the "Boolean Compound Object" button.
In the boolean settings, make sure "Move" and "Subtraction (A-B)" are selected and then click the "Pick Operand B" button. Now select the sphere you just created. This should subtract the sphere from the door leaving an indentation in the door.
Start with the windshield. Hide all unnecessary parts of the car. Set the iterations on the meshsmooth of the body of the car to zero so you have it at low poly. In the front viewport, create a box with 2 length segs, 1 width seg and 2 height segs. Delete the polys at either end of the box so that you have something like what you can see on the left.
Now you have to align the box with the edge of the windshield where it will be. Once you have it aligned, you can start shift+dragging the edges out to form the shape of the windshield. Just shift+drag them around the windshield area as shown below. It will take a lot of tweaking to make it look lright. Mirror it to the other side of the car. Right is what it looks like mirrored and smoothed.
You might as well also put in some glass. A while back you detached the polys that were where the windshield glass should be and hid them. Unhide them and make them double sided like you did with the door. The windshield glass should already be in the correct position but you may need to do some tweaking. Mirror it to the other side. Now you can repeat the process for all the remaining windows. The door windows are a little different but the method is still the same so you should have no problem. Just take your time and don't rush yourself. After all that you should have something like this:
By now your model should be getting pretty big and it must be getting heavier on your computer. To avoid too much slowdown you should hide parts of the car that you are not working on. This will be easier on your computer and will not slow down your work. You can also turn down the number of iterations on your Meshsmooth modifiers and turn them up only when you want to see what the surface will look like smoothed. Meshsmooths will quickly bog down your machine, especially if they are at 2 iterations or more.
Ok, onwards! I just realized that we forgot to do the second rear door handle. This is no problem, we can just do it now. It's pretty straight forward and you can do it the same way you did the driver door handle. Just start with a box and do some extrudes and bevels until you have the desired shape and then smooth. Depending on your references, the handle is likely to be different from the one I found so just model the one you have in your references. The one I decided to model is shown below but there are many different types of handles that you could use. Position the handle in the correct position. I made mine very simple but you can make it very detailed if you plan on having close-ups of it when you do your final renders.
This is the reference pic that I used:
Proceed to the next page for some on the Vents!