Just like your home computer, if you deploy a technology such as navigation to a public medium like bluetooth and the internet. What would we expect? At present the cars are using computers to drive the engine and break systems. But navigation and internet access is not part of that, and probably never will be. Except where already applied by mass transit. Sophisticated trucking companies use position data to adjust fuel ratios into the combustion chamber. For example when they are rolling across the great planes of the USA they can have their fuel mixture backed off via a GPS system and when they reach the high plains and then Denver the fuel ratio is adjusted accordingly to enable and increase in forward momentum. This saves a ton of fuel. But it is also not public. In fact it's a sat channel.

Not many ambulances or firetrucks use on board navigation. It's too expensive to build private infractructure and is inaccurate and unsecure when using a public medium such as bluetooth and a cell phone. You wouldn't open up a police network to the internet without a VPN, why would you do the same in their cars? What I would worry about is all the 9/11 call centers are using Windows NT and Dos based systems. And they are tied together with loose security controls to ouside agencies, such as the Sheriff Dept, Highway patrol, FBI, etc. They just "trust" one another and in most cased the people maintaing the systems are a contractor so there is another interface.

Those windows imbedded devices aren't the same as the windows you surf the web with. All the crap is removed and they are locked pretty decent but any device can be exploited. How many NT and Unix based patches to we see for CISCO devices a year? Yes CISCO used NT. And counter measures are built into critical, life threatening systems.

As for taking a step back... Air travel would not be safe without computers. In fact modern flight models would not be possible without a computer making tiny correcting adjustments to airflow over it's surface. The plane would drop out of the sky. Imagine managing traffic flow in heavy corridors without computers monitoring where the cars are stopped and where they are flowing and adjusting patterns. Cars are also much safer, anyone who has had antilock breaks, or traction control knows what I mean. And I don't know for sure but I bet some imbedded computer deploys the airbag as well. As for disabling a vehicle... moth balls, sugar and knife are MORE effective.

Airplanes operate Navigational Guidance in a number of ways, they aren't very suseptable because they are not public. And one would have to circumvent the wrath of well funded national and international agencies with police powers. First the pilot has a human navigator and can fly with NO external guidance. Then they have ground based radar in the form of airport approach control and segmented corridors that handle traffic monitoring outside the airport control. Then they have navigational beacons such as a VOR or other devices that get them within visual of a runway. Then the have glide slope radiators at the end of the runways and then GPS and then manual over ride. I am worried about the guy not shutting off his laptop during takeoff and external radio interference more than someone breaking one of the systems and feeding false information to a plane comming in for a landing during a fog, like in the movie Die Hard X. Wonder why the other Airports in LA or the Regional Control center didn't just radio the planes and tell them the Airport was under siege by terrorists who adjusted the Glide Slope to be a few hundred feet off?

And we saw what happened on 9/11 when a breakdown in trasportation system was discovered. They didn't use a computer virus.