Think about this..

The Geo-location data from a driver's cell phone can track a person, right?

All they need to do is track BOTH Anne Heche's driving pattern(what road she normally drives) and the find anyone else's car that travels in the opposite direction of Anne's car (that has a hack-able engine) and/or even install a remote steering device on that person's car..and then all you have to do is wait until BOTH of them take their normal driving routes again ..and when both cars(each with the planted gps devices on them) sense each other and their distance is close..they simply make them converge to the same GPS location..and...Blammo!