It's just familiarity. You use these scales of measurements to compare it against others. By itself it's just a useless number/calculation unless you have something to compare it with. I'm not familiar with kilometers because I've never used them so I can't gauge it with anything. Think Jarhead, where he uses the length of football fields to judge a distance, it's the same basic principle.
It's quite odd, here in the UK we use the metric system for just about everything now, except road signs, markings etc. which use Miles and yards for smaller distances. I was also taught to use stones and pounds for weight measurements, whereas in the US (Where I believe it's predominantly imperial?) they use Kilos for weight which is a metric measurement (I think, is it the same as Kg or is there a subtle difference?).
Case in point. I hate the imperial system, because I always have to question how close a yard is to a meter, how close a mile is to a kilometer, how many feet are in a mile, and so on. However, I have some weird preferences that I've developed over time.
When drawing, I always use centimeters to measure things equally; for example, if I'm measuring out even-looking letters on a page, I'll go by, say, 3 cm over and over. Also, if I'm using Google Sketchup, I always use a metric measurement system over imperial for any models.
However, when doing construction-related work in real life, I use imperial to measure things out (we're doing a huge reno, so I've been doing that a lot lately), using 1/8ths, 3/16ths, half inches, and so on.
When measuring car speed, I find it difficult to accurately gauge speed in miles if it's roughly under 100-or-more-ish kph. So if somebody says, "I was going 30 miles an hour down that road," it doesn't mean very much to me. However, if somebody says "I was going 90 kph down that road," it suddenly makes a lot more sense.
On the other end of the scale, I cannot for the life of me figure out how fast a car is going when it's hitting its top speed, especially supercars, if it's in kph. I've developed a standard of how fast a car can go based on the 200 mph mark, which was like a milestone for many supercars. (nowadays, there are like, 30 production cars that can breach it, but years ago it was more rare). So if you tell me that the new Porsche 911 Turbo can hit only 160 mph, unlimited, then I'll be a bit disappointed, considering how fast that car is supposed to be. If you tell me it can actually do 195 or 200 mph, then that starts to seem more realistic to me.
Conversely, if you were to tell me that it can do 355 kph, you've just lost me. I have no clue how fast that is, and I always have to put it into miles to gauge it.
Things like this are the reason that some people prefer metric over imperial, but, even though I sometimes use imperial, I prefer metric. I mean, it's so easy, and doesn't require any dumb 1-2-3 counting when figuring out how many thirty-secondths are in that measurement. It's just straightforward.
about it, and I agree multiply miles by 1.6 is a "simplified way to convert". The only problem is that PD doesn't see it that way
