At first it takes dozens of microprocessors running 100 million lines of code to get your new premium car on the road, and this software is only going to get more complex and more complicated. Let's see the aviation technology, before we talk about car computers and software.
The avionics system in the F-22 Raptor, the current U.S. Air Force frontline jet fighter, consists of about 1.7 million lines of software code. The F-35 Joint Strike Fighter, became operational later in this yearn (2010), will require about 5.7 million lines of code to operate its onboard systems.
The Boeing's 787 requires about 6.5 million lines of software code to operate its avionics and onboard support. These are impressive amounts of software, yet if you bought a premium-class European import automobile recently, it probably contains close to 100 million lines of software code. All that software executes on 70 to 100 microprocessor-based electronic control units (ECUs) networked throughout the body of your car.
The radio and navigation system in the current S-class Mercedes-Benz requires over 20 million lines of code alone and that the car contains nearly as many ECUs as the new Airbus A380 (excluding the plane's in-flight entertainment system).
Software in cars is only going to grow in both, amount and complexity. Cars will require 200 million to 300 million lines of software code in the near future. Even entry level cars now have 30 to 50 ECUs embedded in the body, doors, dash, roof, trunk, seats, and just about anywhere else the car's designers can think to put them.
That means that most new cars are executing tens of million of lines of software code, controlling everything from brakes to the radio's volume. Automobiles are no longer a battery, a carburetor, spark plugs on four wheels. Today's automobiles are highly sophisticated, modern in their ever evolving complexity. When car manufacturers design their new cars, their goals to save energy, reduce emissions, and improve safety. There is no way to do this without microprocessors and without the specialization of car's electronics in particular.
Today's European cars embedded software system and their multiple networks analyze hundreds of thousands of inputs from multiple on board computers and their sub systems. The software deals with high speed data network on fiber optic systems, from engine management to transmission and dynamic stability control. Not to forget the safety devices within the network of a modern high tech automobile, and the list goes on.
For example, BMW's high end models from 2009, equipped with BMW Assist system, which features a risk of severe injury calculation based on information gathered from the car's air-bag controller and its other ECUs, which will inform accident response teams not only where the accident took place, but the likelihood of passengers being severely injured.
To design and produce, and maintain an electronic device like a car computer is not that simple. For the today's premium BMW, Porsche or Mercedes, the cost of software and car electronics can reach 35 to 40 percent of the cost of a car. For do it yourselves keep in mind, there are electronics which need special care, for instance you should not disconnect the vehicles battery prematurely because the the electronics are alive and waiting for instant command for 5 minutes.
Also the DVD player on earlier versions may fail if disconnected while it's powering down. If you try to fix it yourself a small mistake can cost you a lot.