The speed thing would be difficult for me as I'm into car culture so with that I'm far too used to MP/H.

Speed limits and driving would be easy as I have a VW with nice clear gauging for both speeds and my info center I think can be switched over anyways.

Horsepower/torque numbers are also what the fuck. That might be a British thing though. What is the most common measurement for that outside the US?

The temp thing I still don't think I could ever change. Not like I would do it in a way that would affect people.
I already use celcius as much I can outside of temp.