[Fat Charlie]

The conceptual point has nothing to do with metric, but with how you want to see your results. I spend my time by the hour, and speed limit signs tell me how far I can legally go in one of them. It doesn't matter whether or not I think in metric to understand them. I buy gas by the gallon, and our system that sucks tells me how far one of those gallons can take me. Simple math can convert that to metric without having to rethink everything.

MPG, MPH and KPH are all on the same page, no matter what yardsticks they use. To be consistent with L/100KM, speed limits would need to be expressed in H/100KM. I can't see a cop saying Sir, I clocked you at 49 minutes per 100 km. That's eleven minutes under the posted minimum! I'm in a good mood today, so I'll only write you up for 51 minutes. That won't add as many points to your license.

I generally go through CND once a year, and I'll make you guys a promise: when you change your speed limit signs to match the backwards math you use to express fuel economy, I'll start writing letters to my congresscritters pestering them to change our signs to the same format.