alt Hacker News> If cars match speeds across lanes, it impedes faster traffic.
I think this undersells it a little. It does not just impede faster traffic, when the lanes are pacing each other it makes navigating harder -- simply switching lanes is more difficult. The highway moves so much more efficiently with a small but steady difference in speed between each lane.
> Results: A 5-mph increase in the maximum state speed limit was associated with an 8.5% increase in fatality rates on interstates/freeways and a 2.8% increase on other roads. In total during the 25-year study period, there were an estimated 36,760 more traffic fatalities than would have been expected if maximum speed limits had not increased—13,638 on interstates/freeways and 23,122 on other roads.
https://www.iihs.org/research-areas/bibliography/ref/2188