Anything is possible these days, even the NSA possibly getting involved in "wet work". However, there have certainly been some stories in the past few years about the security problems found in cars with OBD-II computer controls.
Here's one: http://www.caranddriver.com/features/can-your-car-be-hacked-feature
In some of the other stories on this, chase vehicles were used to take over critical systems (throttle, brake, etc.) When you factor in the resources that the government has (such as full access to the OBD system code), the possibilities get very ugly.
I think I'll hang on to my '64 pickup.
-PJ