I have an extra-curricular activity that I attend three to four days a week, and the route I've been taking will start to get a significant amount of increased traffic. I had forgotten about an alternative route to get there, but when I looked it up, it's actually 1.6 miles shorter. The kicker is -- I had also forgotten about this -- the posted speed limit is 55 mph for about a 1/3 of the trip.
I decided to test it tonight, and sure enough, I gained ~ 2 mpg from my normal trip mpg. So that's 3.2 miles saved and 2 mpg gained just by taking an alternate route.
I might not be able to take it Fridays due to traffic. I'm a little leery, but I might test it anyway.