I've been on plenty of flights where displays and cockpit announcements were in metres (altitude) and kilometres (distance + velocity) - as well as Celsius for outside temperature.

If you fly a plane (not just on a plane), those are nautical miles, not land miles. And speed in knots. And rate of climb in ft/min.

My trip computer does litres per 100km. I drive a Citroen C5 and it has kph on it as well as mph. My satnav usually reminds me if I'm driving too fast (in kmh which is handy) and that results only in me watching out for speed cameras and the fuzz :)

I don't fly - I drive if needs be. I frequently drive around Europe as it's easier than dealing with flights and a damn sight more comfortable, reliable and cheaper than flying. I can drive to Leipzig from London in about 10-12 hours.

I'm in a country that uses the metric system, and have never cared about learning the exact equivalent of screen sizes. I just intuitively know, (from using and looking at them in the office or the store) what a 13", 15", 24", 40" etc screen is like -- and I never bothered to do the conversion at all.

It wouldn't even really help, because even if a knew the measurement in metric units, it would mean very little to the actual feeling of the screen, especially considering the variety of aspect ratios and that the display size measures the diagonal.

>The trip computer on your car will tell you miles per gallon.

All trip computers I've even seen can be set to show metric units.

>Even if you ignore speed limits, your speedometer gives you your speed in MPH :)

Still no need to do any conversion. I've travelled thousands of miles in the US (Route 66 and coast to coast several times), and I never wondered "Hmm, how many km/h are 70 mph?". I just needed to keep an eye on the speed limit signs to keep below that, and drive as fast as the car/road called for. Intuitively, not by translating to metric units.