On Thursday, February 19, 2015 at 11:46:10 AM UTC+13, Dan Marotta wrote:
Why can't we all go metric?* Because 10s of litres per 100 miles is
a silly measurement compared to miles per gallon.

It depends on whether you're filling your tank and then asking "ok, now where can I go to?" or saying "I want to go to X, what will it cost me?"

The latter is, I would submit, more generally useful.

Quick, if you're going to travel 1000 miles, is it a bigger saving to get 22 mpg from something that was previously doing 20, or to get 45 mpg from something that was previously doing 40 mpg?

In fact, the former will save you a lot mo 4.5 gal vs 2.8.

Which can be readily seen from converting to l/100 km: 11.76 vs 10.69 and 5..88 vs 5.22. The difference between the first pair is 1.07 l/100km while the difference between the second pair is only 0.66 l/100km.


Same with knots airspeed and lift/sink vs. km/hr and m/s.

I don't care what the units are, only whether it's up or down, and getting better or worse.