I have experienced about an 8% improvement lately on my energy efficiency with my Model S. I drive the same route to work and back, traffic hasn't changed, weather, tire inflation and other obvious influences haven't changed either, but instead of using my very predictable 279-280 wh/mi. of energy, for the past week or so, I've been using more like 257 wh/mi. on the same routing. The only change I can think of is that I upgraded to software version 6.1 (2.2.92) about that time. I'm going to keep recording my energy efficiency for another week or so before installing version 6.1 115 because I want to collect more data points before possibly changing the equation. I also notice more miles remaining when I reach work each day (a 40 mile commute), but I start the trip with a fresh charge and with the usual number of miles. The only other variable I can think of is perhaps I am using less air-conditioning, but the weather hasn't been especially cool this past week. Has anyone else recently experienced an unexplained efficiency improvement?