You use imperial units but you (your merchants anyway) are required to use metric alongside them, as I understand it. Road signs are all still in miles though, aren't they.

For a long time there was a mix in Ireland that I never considered confusing (because I was so used to it) until a Greek friend pointed it out to me - all our roadsigns for distance were in kilometres but our speed limits were in MPH. All in k now.

The other thing that surprised him was that the speed limits for corners / twisty roads were not suggestions they were 'drive any faster than this and you're in the ditch, mate'