Let's start at the beginning and understand the "cinematic origins" of the Batmobile. In other words, let's understand how the car works in the movie.
The first thing you have to understand about Batman is that he must have a car. Unlike Superman, who has superhuman powers, Batman is a normal human being who gains all of his advanced capabilities through ingenuity and technology and usually a combination of the two (see How the Batsuit Works). He can't shout "Up, up and away!" and fly through the air. Batman needs wheels to get around.
The second thing to understand is that, in this movie, Gotham City is portrayed as a highly dysfunctional version of New York City on steroids -- there are surprises and obstacles at every turn. So Batman needs a rugged car.
The third thing to understand is that Batman cannot, realistically, construct the car himself. Ordering all the machine tools and parts and assembling them in the basement would give away his secret identity.
So in the script, they create a mothballed military vehicle built by Wayne Enterprises. Batman requisitions this vehicle for his own purposes and paints it black to match his color scheme. The Batmobile also gains some rather remarkable abilities. For example:
- It can go very, very fast.
- It has a jet engine that allows it to jump/fly through the air much farther than any normal car could.
- It has two driving positions -- one for driving and one for jumping/flying.
- It has stealth capabilities, and part of the stealth mode is a silent, electric-motor drive.
- Getting into and out of the car is "unusual" to say the least. There are no doors -- instead, the car "opens" somewhat like a flower.
Nathan Crowley is the man who had to take that cinematic vision of the car and bring it to life on film. Now, the thing that you have to understand about Nathan is that he is a very physical guy...