A deliberate obstruction
"That doesn't explain why you didn't give us a copy of your draft.
....It is still responsive to the committee's request"
This is on page 46 of the transcript of a May 2010 interview of Exponent's Dr. Shukri Souri by investigators and counsel for the U.S. House Energy & Commerce Committee.
Do I recall correctly that the Committee later memorialized this sin in a letter to Toyota? Maybe the problem was fixed later and maybe it wasn't. Congress can be even more secretive than Toyota.