Glad I found this post again, since I've been wondering about an interview at the Arizona State Fair back in October 2013 I had read where Branden Carey mentioned that they actually had 25 prototypes in production at the time. Was he misquoted, or is it possible they actually have a couple dozen P4's stored around somewhere?
There is only one P4 built very late 2013 and unveiled mid-January 2014.
It is possible he misspoke, was misquoted, or his quote was taken out of context. According to the plan at the time EM was supposed to build a test fleet in fall 2013. That plan fell apart when EM encountered the delay in securing the plant which also cost EM the funding they had lined up which was supposed to pay for this testing.