EMI and FADEC
There have been several comments thus far citing the presence of Mysterious Electromagnetic Interference Coming From an Indistinct Black Box of Unknown Origin and Attached to a Car, and as one of the maligned ground crew (avionics), it really makes me smile.
Most of these systems are fairly well shielded, as is the wiring that is associated with them. The idea that some random radio or another causing these things to fail (and also causing the redundant systems to go as well) is something that I don't think is within the realm of that which is reasonable.
Something that ought to be established here is that there are tests that these systems go through to ensure they will stand up to electromagnetic interference (EMI) far beyond what they would see in a lifetime of normal operating conditions. I've been working with aircraft electronics, avionics, and related systems for about 15 years now and have seen one EMI induced failure.
That specific incident was caused when the aircraft I was working with was hit by the beam from a U.S. Navy phased-array radar at approximately 0.5 miles from the antenna. It ought to be understood that this particular radar isn't something that you could easily vehicle mount, as the antennas are designed for shipboard use and have output power in excess of 4 MW. (I don't care how big your alternator is, or what kind of capacitors you've got wired up to the stereo, you aren't lugging one of these around under your jacket.)
Furthermore, the specific failure was limited to a piece of equipment that dealt with the reception of RF at that particular band. (Melted receiver module, lots of smoke, otherwise harmless.) What I would like the tinfoil hat set to note here is that the FBW and automatic flight control systems in the plane worked fine before, during, and after the event. What I would also like them to note is that a common thing to do with this particular receiver is to wrap it in silvered barrier paper (read: plasticized aluminum foil) to prevent this sort of thing from happening. (For those of you in the tinfoil hat set that may be a little on the slow side: I just said that wrapping your heads in tinfoil really does work. However, fine copper mesh works much better. You should also wrap it around your entire body, not to forget the bottoms of your feet, because the signals can still get under the hat and into your brains.)
I would be positively amazed to find that the mishap investigation cites EMI-induced total FADEC failure as the sole primary causal factor for the event. Again, the probability of the entire system, as well as the redundancies, failing simultaneously is too high.