The metric system was introduced in Napoleonic France, if remember my
history, as a democratic reform to aristocratic systems of measurement based
on the king's feet, thumbs, etc. (Again IIRC, the Spanish word for inch is
"pulgada," related etymologically to "pulgar," thumb, as is the French word
"pouce".) The same reforms also gave us such niceties as the public museum
and the zoo. Curiously, the only reform that did not last through the 19th
century was that of the calendar. However this all may be, the metric system
is quite simple once you get used to it and start thinking that way.
Otherwise, how could anyone fill up a tire or draw architectural plans in
Europe? The only thing I could never get used to was the Celsius temperature
scale, which would have us believe a sweltering beach in mid-summer is only
27 degrees...and now, back to our regularly scheduled Vanagon programming.

BTW, mileage is also figured "backwards" in France: how many liters of gas
does it take to go 100Km? But again, once you get used to it, it doesn't
make any difference. Now back to our regularly scheduled...