Supposedly a multiplier of the average traffic speed on the road. 1.0 = average. .9 = 10% below the flow of traffic and 1.1=10% above.
I typically do my planing at 1.1, and we typically drive about 5 over the posted limit. That's resulted in estimates by EV Trip Planner that are very close to actual RM used. We did a 4,250 mile road trip last summer, and planned the entire route using EV Trip Planner -- most of the estimates were within 2 RM of actual. All were within 5 RM...