Ignoring the massive disruption that going below the speed limit causes and the increased aggression it instills in other drivers who understand how to follow the rules of the road:
A sedan is, on average, 1302 kg according to a random quora page. 45 miles per hour is approximately 20.116 meters per second. So about 26.191 newton seconds. People aren’t surviving that.
So unless you are battling entitlement by going thirty miles under the speed limit (which will probably still squish a person but I am too lazy to math it), all you are doing is antagonizing everyone around you while filling yourself with a false sense of security.
Seriously, and I mean this from the bottom of my heart, take a defensive driving course. Defensive driving is about learning to anticipate the drivers around you and how to minimize the chance of a collision. Which is not the law you learned in driver’s Ed. It makes you a much safer driver and will probably lower your insurance premium.
That means driving in a way that doesn’t anger everyone around you and knowing when you actually need to slow down and when doing so won’t help