Used it again on a 60 mile (each way) outing on Saturday and it was still significantly off with my car. Not as much, but still out by over 10% (worse). For some reason, it seems overly optimistic and I am a very conservative driver too.
I'm in the same boat as you for predictions prior to departure. The system does does a good job of factoring distance, speed, current HVAC, and elevation changes.
However, this time of year we're heavily impacted by factors ignored by 6.1:
1) Increased air density due to cold temperatures.
2) Heating (only considered if running when you enter the destination).
3) Higher rolling resistance Winter tires.
4) Snow on the ground.
Once you start driving and over consuming, 6.1 first gradually increases its consumption estimate, then figures out the situation's not going to improve and jumps down to a more accurate forecast. The process then repeats the next time because there is no memory or learning.
Here's an example from Saturday. The car was garaged, but then outside with heat running for 30 minutes before I entered the destination and departed. Average temperature for the trip was -17C/+1F.
Average posted speed limit was 80 km/h, but actual speed was lower. There was a dusting of snow everywhere, and 30% of the trip was on back roads over hard-packed snow. The initial estimate of using 22% (90% to 68%) was too low by 36%, but at least by half way the revised estimate was spot on as I finished with the 60% predicted by the green line.
I never used evtripplanner much before, but its predictions with the default 72F temperature settings are very similar to 6.1's. However, evtripplanner really shines when you enter temperatures and I plan to make a small donation to the site. In other cases, I will let 6.1 account for the 2,000 feet of elevation change between some Superchargers, but I will then adjust for weather on my own.
