[quote name='The Mana Knight']
I still have a lot of difficulty judging the length of the car.[/quote]
There's not really any reason for you to need to judge it. There's a lot of reference points on cars that you can use to know exactly where different points of your car are. They can be a little different for each car, so you need to experiment a little, but they are pretty good rules to follow. The ones that I remember from Driver's Ed (distances may be a bit off as it's been a while, but I think they're correct):
To judge distance of your right tire from a line/curb, etc.
When the line/curb appears to be running into:
-your right headlight--6ft away
-the middle of your car (or hitting your hood ornament)--1-2 inches away
-halfway between that--3 ft away
To judge distance of your left tire from a line/curb, etc.
When the line appears to be running into your left headlight--2 ft?
To determine where your front bumper is:
Before approaching the spot you want to stop at, choose a point about 15-20 ft to the right of it where you want your bumper to be that you will still be able to see when you pull into your spot. As you are pulling up, look to your right at your side mirror. When the point you chose earlier lines up just under your side mirror (or when the line is even with your mirror, different for every vehicle), your front bumper is now even with that point, and therefore your stopping point.
There's another one for telling where your rear bumper is, but I can't remember it. The best way would be to get in an empty parking lot with a long curb and have someone back you up until your rear bumper is even with the curb. Now that you've stopped, notice, as you're looking through the rear passenger-side window, where the curb appears to run into your window. Put a piece of tape there on your window. Now try backing up again without help. When the curb appears to run into your piece of tape, your bumper will be even with the curb.
Those are the ones that I remember, and they help a lot if you're having trouble judging where different parts of your vehicle are. Again, they can vary slightly according to the car, so it's best to find an empty parking lot with someone telling you when to stop, and then seeing what the different reference points look like for your car.
After you get used to the car it just becomes second nature and you don't need to pay so close attention to reference points.