...follow Britain (which voted against metric in the long run - God bless the Brits they voted against the Euro too!)....
The British don't really know what to do.* They sell fuel by the litre, measure road distances in miles, land distances in kilometres, weight in pounds, kilograms, and stones, speeds in miles per hour except where they decided to measure it in kilometres per hour,*and build their vehicles with a mix of standard fasteners (1/2", 9/16", etc) and metric fasteners.* Our Range Rover uses standard fasteners on the frame, metric fasteners on the chassis, body, and engine components (except for the ones that are are standard), and probably if one looked deep enough there are some Whitworth fastners thrown in for good measure, too.