(THE DETROIT BUREAU) — A two-year study looking for possible causes behind Toyota’s rash of unintended acceleration issues has put primary blame on driver error — but the review by the National Academy of Sciences also cautioned that some problems may have been caused by inadvertent interactions involving vehicle electronics — an issue frequently cited by the automaker’s critics.

Though there was no hard evidence of specific electronic defects, the 139-page report cautioned that “the absence of evidence is not the evidence of absence.” Warning electronic faults may be “untraceable,” it calls for stricter government involvement in setting standards for the use of electronic control vehicle systems.

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