"M\xb1qL" -what is this in an apache server access log? Thank you!?

Answer 1

All depends on the rest of the context line. If you are saying this appears all by itself that is strange. If it has a context surrounding it then it may help figure out what that might be.
Since there are many attempts at cross sight scripting these days it my just be part of an attempt to cross inject, or it could be part of a script on your machine.
Check the lines before and after as well as the complete context in which this is seen.