Lots of xp per hour

[makersmark2]

Just so I get this right (and because I have a headache and can't think straight).

According to http://www.wowwiki.com/Formulas:Mob_XP

Red: Mob Level >= Char Level + 5
Orange: Mob Level = Char Level + (3 or 4)
Yellow: Mob Level between (Char Level - 2) and (Char Level + 2)
Green: Mob Level <= Char Level - 3, but above Gray Level

So my lowbie toon is 40 and red to him is 45.
Lvl 45 mobs are the target
Lvl 45 mobs are still green for lvl 48, so that's the max my high toon can be.

Is this the most efficient way? And does this only work for elite mobs?