Meh, it's so little that you MIGHT save yourself a couple gallons of gas a YEAR. Not worth it if you ask me. You're get more out of it if you folded in your passenger side mirror.
Seriously though, I drove around for a MONTH with an ocean kayak strapped to my roof rack (people can vouch for this) and I saw about a 10 mile/tank difference. That's a full blown 11 foot kayak strapped TO my OEM roof rack.
But do as you please. I don't remember making a single one of your car payments.
BTW, that link posted earlier works. Just gotta give it time. Maybe try to right click it and go "save as". Good luck.