GaslessInSeattle said:
"this meter displays the actual traction motor power consumption and the regenerative brake power provided to the Li-ion battery."
Edited...
This means it is NOT an efficiency gauge. Efficiency is how much energy is used to go how far. The bubbles simply tell you how much energy is used/gained by the traction motor. It does not divide by the speed and it does not factor in the hills. For low speeds, before wind resistance takes over as a major source of drag, the bubbles will match the feeling in your butt and that does include up and down hills. When going up a hill, the car slows, but the acceleration feeling in your butt matches the bubbles because the power is either going to kinetic energy (more speed) or potential energy (up a hill), and both have the same acceleration feeling in your butt. At higher speeds, wind and rolling resistance take over as a major source of energy loss, and the bubbles to butt feeling ratio is shifted up the dial. This is high school physics.
This is something the Nissan engineers certainly knew. It is inexcusable that they gave us a gauge that has fooled you into thinking you are getting efficiency information. Nissan could easily have done the math using the computers that the car has, and given us a proper efficiency gauge. They would need to put an accelerometer into the car, because if you only use the acceleration you can determine from the speed of the car, you ignore the hills. You also need to know the mass. The calculation is to subtract the acceleration (the feeling in your butt) from the energy going in/out of the battery (or traction motor if you want to ignore other energy uses). This tells you the energy that can not be recovered. Divide the distance by this number and you have miles per joule, which is the efficiency number you want. (this is the general idea, not the exact formula)
An accelerometer is cheap, and the math is trivial. My guess is that how aggressively you accelerate is not very important for efficiency. If you accelerate like a snail, you will get worse range, but nobody will do this extreme because the honks would be annoying. Similarly if you accelerate hard, you will get worse range. I will bet there is a large range where it does not make any difference how hard/soft you accelerate. I will bet the biggest factor for range is how fast you travel. The optimum is 38 according to something I read somewhere. I will bet that there is a large range say plus or minus 10 miles per hour that all produce excellent efficiency. Above say 45 (my guess) the wind resistance starts rising non-linearly and therefore starts to really hammer your range.
Strictly speaking this efficiency information is not really necessary. The percent of trips where the car is taken to the extreme end of range, where the driver needs to drive efficiently, is certainly less than 1%. I have only heard the lady say I am low on energy 4 times in 4000 miles, and she said it within 4 miles of my home each time. I never had any need to conserve. It sounds like your trip to/from Shoreline to Olympia is extreme and you probably need to drive efficiently. However, I am certain those bubbles are a total distraction. If you are slowing on hills and speeding up on downhills to limit the bubbles, you are not only pissing off drivers behind you, you are worsening your range. The major factor by far, in that trip, is your speed. Set the cruise at some number that gets you there, and your efficiency is most likely maxed. The cruise will prevent the car from going above whatever speed you set, and the higher speeds are a certain waste of energy. The cruise will recover energy going down hill, whereas letting the speed rise will waste it. The gauge is useless, and probably has misled you.
A proper instantaneous efficiency gauge would be useful, but not terribly necessary. The bubbles are completely useless, and the Nissan engineers know this. They knew everything I said above when they designed the car, and it is inexcusable that they put that gauge in there. Not only is it a waste of money, it is clearly distracting some drivers.
We should not give them a pass on a pathetic HVAC system. They should fix it. One very important feature of an EV is instant on heat, and heat/cool without idling a gas engine. Any automatic climate control for an EV should be easier to design than one for an ICE. I expected it when I purchased the car. I was looking forward to a car that had an HVAC that was better than any gas car, precisely because it was an electric car. My 72 cadillac's auto system performed better than the Leaf, and not because it had a huge ICE to generate heat. The Leaf produces plenty of heat too.