I posted "Please complain to Nissan to fix the climate control". In that thread, I argued that the white bubbles are useless and that Nissan should have provided a proper efficiency gauge. It seemed clear to me that most readers did not comprehend what a proper efficiency gauge would do and show, so I thought I would describe it here.
With the current white bubbles, you have no way of knowing how many bubbles will maximize efficiency when accelerating or decelerating. We also can't determine easily what speed is the most efficient and how costly other speeds, either faster, or slower are.
A proper efficiency gauge would measure how much of the electricity going to the motor is going into kinetic and potential energy. To do this, they need to measure the acceleration of the car. They can do that by reading the speed, but that would not handle hills. If they put an accelerometer into the car, it would handle hills fine. They would want to know the mass of the car and passengers. If they assumed some constant for the mass, and the mass was greater, then acceleration would appear very poor but deceleration would appear correspondingly better. I suspect that they could easily estimate the mass after one acceleration/deceleration cycle after any door opened/closed event and adjust the display.
This gauge would not need a reset feature like the gauge on the main screen, because it would not need to average energy use over some time. It would measure the lost energy every fraction of a second. It would not jump up and down as you accelerate and decelerate like all MPG gauges do and like the MPKw gauge does, because the lost energy does not jump up and down with the pedal.
I am guessing that there's little difference between accelerating hard vs soft, and thus the gauge would read a relatively similar value regardless of how hard you are pushing on the go pedal while you accelerate. As the speed increases the gauge would initially read a poor efficiency because going 1 mph is probably very inefficient, then peak as you pass through the optimal cruising speed and decline as you go faster.
The gauge could have 3 different readouts, or modes.
1) Percent efficiency - You simply maximize this percent at all times and you are doing the best you can possibly do. This could also be expressed in terms of Miles/Kw.
2) Projected range (round trip) - This would tell you how far you can go if you continue driving like this and return home. In this readout, it assumes the end point will be at the same altitude as the starting point. For example, if you have 60 miles of juice, and you drive up some big hill for 30 miles the current GOM might read 20 miles left. In contrast, this gauge would read 30 miles left, because this gauge would know you are up a big hill. The very cool thing about this gauge is that it will instantly tell you what speed to go at. If you accelerate up to 70mph, the gauge will drop immediately to tell you how far you can go at 70mph. If you relax and drop back down to 60mph, the gauge will rise.
3) Projected range (one way) - A basic implementation would in effect discard the built up potential energy, so the miles to empty would read 20 in the hill example above. A cooler implementation would use the Nav, your destination, and altitude information to know what to expect.
The engineers could do a bunch of cool things with the nav system. I am not certain, but I assume that the map data has road speeds, and the routing is optimized for time. This could route for best energy consumption. Knowing the amount of energy in the pack, and whether this is a round trip or not (electricity at the destination), the nav could tell you whether you need to limit your speed or not.
With the current white bubbles, you have no way of knowing how many bubbles will maximize efficiency when accelerating or decelerating. We also can't determine easily what speed is the most efficient and how costly other speeds, either faster, or slower are.
A proper efficiency gauge would measure how much of the electricity going to the motor is going into kinetic and potential energy. To do this, they need to measure the acceleration of the car. They can do that by reading the speed, but that would not handle hills. If they put an accelerometer into the car, it would handle hills fine. They would want to know the mass of the car and passengers. If they assumed some constant for the mass, and the mass was greater, then acceleration would appear very poor but deceleration would appear correspondingly better. I suspect that they could easily estimate the mass after one acceleration/deceleration cycle after any door opened/closed event and adjust the display.
This gauge would not need a reset feature like the gauge on the main screen, because it would not need to average energy use over some time. It would measure the lost energy every fraction of a second. It would not jump up and down as you accelerate and decelerate like all MPG gauges do and like the MPKw gauge does, because the lost energy does not jump up and down with the pedal.
I am guessing that there's little difference between accelerating hard vs soft, and thus the gauge would read a relatively similar value regardless of how hard you are pushing on the go pedal while you accelerate. As the speed increases the gauge would initially read a poor efficiency because going 1 mph is probably very inefficient, then peak as you pass through the optimal cruising speed and decline as you go faster.
The gauge could have 3 different readouts, or modes.
1) Percent efficiency - You simply maximize this percent at all times and you are doing the best you can possibly do. This could also be expressed in terms of Miles/Kw.
2) Projected range (round trip) - This would tell you how far you can go if you continue driving like this and return home. In this readout, it assumes the end point will be at the same altitude as the starting point. For example, if you have 60 miles of juice, and you drive up some big hill for 30 miles the current GOM might read 20 miles left. In contrast, this gauge would read 30 miles left, because this gauge would know you are up a big hill. The very cool thing about this gauge is that it will instantly tell you what speed to go at. If you accelerate up to 70mph, the gauge will drop immediately to tell you how far you can go at 70mph. If you relax and drop back down to 60mph, the gauge will rise.
3) Projected range (one way) - A basic implementation would in effect discard the built up potential energy, so the miles to empty would read 20 in the hill example above. A cooler implementation would use the Nav, your destination, and altitude information to know what to expect.
The engineers could do a bunch of cool things with the nav system. I am not certain, but I assume that the map data has road speeds, and the routing is optimized for time. This could route for best energy consumption. Knowing the amount of energy in the pack, and whether this is a round trip or not (electricity at the destination), the nav could tell you whether you need to limit your speed or not.