From trunk to hood (or is it hood to trunk?) of a car; metonimically, the whole car; by extension, the entirety of anything. Weirdly, the expression is almost exactly as often rendered as “from bonnet to boot”: 283,000 to 282,000, according to Googlefight. Still rare in U.S., and used mainly in automotive contexts. “One of the many options: wide racing stripes from bonnet to boot.” (New York Times, October 11, 2006)/”Boot to bonnet low cost maintenance.” (www.miniusa.com, accessed March 22, 2011)
notoneoffbritishisms.com 