I am currently experimenting with ways how to drive my Tesla as energy-efficiently as possible, and I have found a way where preliminary results show a 10% reduction in consumption.
Story: I currently have a loaner, provided by the fantastic Denmark Tesla team, when my 12-V Battery malfunctioned for the 3rd time in 3 weeks - they actually transported a loaner 400 miles to Stockholm and brought down my car for repair - WOW!!
This loaner, though, consumes about 10% more energy than my proper car with identical trips, identical settings and, as far as I can see, identical driving. Because of an imminent long haul this concerned me very much, so I started to think of ways of bringing down the consumption. I got the advice from a Tesla man: drive it as you would drive an ICE.
OK, fine. I have developed a style of driving with ICE:s that invariably beats their own consumption figures (and we all know that they are the "optimal" ones anyway). It is quite easy - roll the car in Neutral as much as circumstances allow.
I tried this with the loaner, and it immediately yielded really good results - minus 10%, from 310 Wh/mile to 278 Wh/mile in 40 degrees F.
The Tesla is built with such a small wind and rolling resistance so that these 2 factors coupled with the huge mass makes the Tesla roll "for ever", especially in a down-slope. If there's just a small decline it doesn't even lose speed.
The gearbox is so well-made that I learned in less than 2 minutes how to change back and forth between Drive and Neutral without anyone noticing anything.
So, if you free-roll and want to lose speed, put it in Drive and engage re-gen. If you want to keep the speed or increase it, just put it in Drive and - well, drive.
The Cruise Control doesn't do this well - it constantly gives small "puffs" of energy and then brakes, for instance when you reach a small hill, and the re-gen cannot be 100% efficient, so you lose more than you gain, whereas, if the hill is small enough, you just roll over it in Neutral or you see it coming and accellerate slightly BEFORE the hill and roll down after it (never accellerate uphill, if it can be avoided).
This car has such eminent rolling features that this can be done without at all disrupting the traffic flow, if applied intelligently (mostly meaning rolling downhill, but also anticipating a traffic jam or light).
I called Tesla and asked them if this could in any way, shape or form damage the car (I am driving a loaner, and I am much more careful with other people's properties than with my own), and the answer from the Danish SC was an unequivocal NO.
My lifetime average consumption (incl. the multiple showing-off accellerations in the beginning - I am only human...) with my proper car is 289 Wh/mile, with the temp has varied between 29 F and 50 F. Applying the free-roll system, I think I will get it down to 260 or thereabouts. Will keep you posted.
Would be interesting to hear, if anyone else has tried this and their experiences.