some life choices and their numbers:
from Oct 2006 to march 2010, i drove near exactly 160,000km. that's about 3800km a month. i can drive average 450km per tank of gas (its very steady at this value be it city or highway seems to make no difference), that's 8 tanks of gas per month.
in march 2010 i got a new job in the same city i live in. and now its march 2015 and i'm at ~240,000km. that's about 1300km a month or 3 tanks of gas.
i'm saving 5 tanks of gas per month, or that's about 5*45$ = $225 per month or $2700 per year. its been 5 years.. so i've saved nearly $15K by working local. not to mention i got back 12 hours per week from no commuting and mean time before life expectancy went up by not having to drive on the highway
all in all ... working local? one of the top 5 best decisions of my life.