Boeing’s 787 Dreamliner is one of the most advanced passenger jets ever built. It needs about 6.5 million lines of software code to run its avionics and onboard systems.

The average car needs far more. Analysts at Goldman Sachs estimated that by 2020, a typical vehicle carried about 200 million lines of code, roughly 30 times the 787.

A modern car is a rolling network of computers. Instead of one central brain, it has dozens of small control units, often 100 or more, each running its own software for the engine, brakes, airbags, seats, windows, climate, and screens. 

Ford CEO Jim Farley has noted that the software in his company’s vehicles is written by about 150 different companies that rarely talk to each other. Much of that code repeats from one unit to the next.

The 787’s code is lean by design. Every line of flight software must pass some of the strictest safety certification in the world, so aircraft engineers keep it as compact as possible. More code does not mean smarter code.

The growth has been staggering. In 1981, General Motors ran about 50,000 lines of engine control code across its entire domestic passenger car lineup. Today a single average car carries 4,000 times that.