Get it working, measure, see if optimizations are required.
Optimizations (I.E. rewriting stuff in assembler) frequently obfuscate the code, so should be done only as necessary.
It would be nice (though it is terribly unimportant at this stage) if the output from the cpu could drive something like this, then users could see something interesting:
http://www.sparkfun.com/commerce/pro...roducts_id=461
OF course I would want to mix in a vehicle speed signal so that watts/mile could be displayed, then buttons and yadda yadda
But not important for version 1, think "scope control" for now.