Sorry I can't offer up any better explanation for my Sig #802 coming earlier than other, lower numbers. Geography and finalize date seem to make the most sense to me. Unlikely parts availability or QC, since my VIN# is very low (209). I'm not friend or family. Don't know anyone at Tesla, have never even attempted to sit in a roadster (at 6'3 and 310# I doubt I could get back out), and I made my reservation end of November 2011. Received my counter-signed pre-mvpa on June 15. As far as them assigning an already under production car to you when you finalize, I don't think so. I tried to change my wheel selection and they said it couldn't be done once production had started because the whole manufacturing process is locked in when they start the build and the options (even wheels} have some impact on build parameters.
And just in case it does have something to do with parts availability, I'm getting non-perf, sig red, black leather, obeche, silver wheels, paint protection. No jump seats.