Clyde heard about the Jeep that got hacked and worries that it could happen to his car since he connects his phone to the car with USB. Leo says that simply connecting the phone to the car stereo isn't sufficient for this. The Jeep hack involved using the car's built-in 3G access. The real flaw is that the entertainment unit of the car and the computer running the car (braking, ignition, etc), are not physically separated. They are connected in many cars through the CamBus, or internal car network. So if a hacker could find a vulnerability in the entertainment system, he might be able to cross that software only barrier into the car's electronics.
Car manufacturers will be addressing this, but it could take some time for it to make its way into production. This isn't something to panic about, though. Someone would still have to target Clyde in particular, which is highly unlikely. Clyde was concerned about terrorism, but Leo says they aren't just looking to get individuals. The bigger concern is something like our electrical grid, for instance. If there's cyber terrorism it will happen on a much larger scale.
(Photo credit: Rudolf Simon)