Car security

Complex Car Software Becomes the Weak Spot Under the Hood

Shwetak N. Patel looked over the 2013 Mercedes C300 and saw not a sporty all-wheel-drive sedan, but a bundle of technology.

There were the obvious features, like a roadside assistance service that communicates to a satellite. But Dr. Patel, a computer science professor at the University of Washington in Seattle, flipped up the hood to show the real brains of the operation: the engine control unit, a computer attached to the side of the motor that governs performance, fuel efficiency and emissions.

To most car owners, this is an impregnable black box. But to Dr. Patel, it is the entry point for the modern car tinkerer — the gateway to the code.

“If you look at all the code in this car,” Dr. Patel said, “it’s easily as much as a smartphone if not more.”