Unless your going on a long trip going 80 vs 55 will saves you less than 5 minutes on your daily commute, plus more gas is used.
I hope you don't drive 55 when the speed limit is 65, that ain't cool.
If you want to go slow, drive the LIMIT, in the right lane, not 10 under, or you are a hazard, provided you can do the limit.
traffic flows when all are going at a fairly close speed . you can't have people going 50 and 90, 60 and 70, or 70 and 80 is OK.
Drive at the speed of traffic people, if you like to drive slow say 60-65, and your on a road where the traffic is moving good, drive 70-75 in the slow lane, just to keep pace with traffic, you won't get a ticket, if you're going 75 in a 65, and everybody else is at 80 +....it's safer this way.