Whether individual reports of runaway Priuses are true or not, the sheer number of complaints and accidents would indicate that many vehicles in Toyota's lineup may have deep underlying issues. These issues are exacerbated by the fact that many American drivers are unaware of all the means at their disposal to stop their vehicles.

The feds are now examining a rather wild theory -- that cosmic radiation may be causing some of Toyota's electrical issues.  The feds received an anonymous tip from an industry source that Toyota's microprocessors, memory chips and software may be more sensitive to cosmic rays than its competitors, causing increased incidences of malfunctions.  Such problems are commonplace with airplanes or spaceships, raising the need for extremely robust electronic designs.

Sung Chung, who runs a California testing firm, says he believes the tipster may be correct.  He states, "I think it could be a real issue with Toyota.  [But] nobody wants to come out and say we have issues and we need to test."

Electrical interference could help to explain the unintended acceleration afflicting 13 models across Toyota's lineup, or about 5.6 million vehicles in total.  While software and hardware can compensate, to an extent for cosmic interference, cosmic rays can potentially cause the kind of unrepeatable "single event upsets" that could add up to many of the 3,000 complaints against Toyota received by the National Highway Traffic Safety Administration since 2000.

William Price, who worked at a jet propulsion laboratory studying extraterrestrial electromagnetic interference (EMI) for 20 years, comments, "[It] occurs virtually anywhere.  It doesn't happen in a certain locale like you would expect in an electromagnetic problem from a radio tower or something else."

A Toyota spokesperson in a brief comment to Freep.com said that Toyota's protections against extraterrestrial EMI were "robust against this type of interference" and that its vehicles featured "absolute reliability".

Toyota may not be the only one susceptible to cosmic EMI, though.  Other manufacturers likely would have similar occurrences even in more reliable designs, albeit less frequently.

Cosmic EMI may turn out to be of little concern, or it may turn out to be a major problem with the increased use of in car electronics.  The auto industry used to use mechanical links, but now uses electrical throttle controls to save weight and space, and make other technologies possible, such as stability control.  Those benefits could come at a cost, though.

Update:

There's a lot of confusion about what "cosmic interference" or "cosmic EMI" is.  "Cosmic interference" or "cosmic radiation" can mean one of two things:
First, disruption due to cosmic rays, which are primarily composed of protons (hydrogen ions), helium nuclei (alpha particles), and high energy electrons.  Secondly, cosmic bodies like the sun can transmit self-propagating electromagnetic waves through the vacuum.  These waves can be referred to as "cosmic EMI".  Cosmic particles can also cause damage, but aren't referred to as EMI.  This article is referring to both cosmic rays and cosmic electromagnetic radiation.