Maybe no one falls asleep while driving that fast, but Google suggests that people can drive pretty fast once they fall asleep:

http://boston.cbslocal.com/2012/01/03/sources-lt-gov-murray-... http://www.oregonlive.com/pacific-northwest-news/index.ssf/2... http://sandra.visionsmartnews.com/randolph-county-nc-school-...