Mercedes Guess O Meter (GOM) range prediction issues
The GOM is not actual range autonomy of the vehicle in any logical future looking manner. Its data is ALL derived from past driving, usually quite poorly.
For the GOM to mean anything, you must reset all the consumption rate data on the center dash. Use the up and down buttons on the left side of the steering wheel.
When you reset everything, the GOM will read (plus or minus a mile or two):
31.5kWh "extended" charge - 94 miles
28.0kWh "normal" charge - 87 miles
In both cases, the battery percentage will show "100%".
NOTE: YOU MUST RESET THE METER TO GET THESE VALUES. The reset is done with the left steering wheel buttons. Scroll to the driver's side dash display on the reset page with the up and down arrows, and follow the instructions to reset. Press the center button (not the arrows) in the left hand side of the steering wheel when on the reset page and it will prompt you to reset, Yes or No.
Make sure you reset the correct page, because two of them look similar... one is for RESET and the other is limited to reset since START. It is only necessary to reset if you want the GOM to show 86/88 miles for a normal charge, or 93/95 miles for an extended charge. The battery % will show 100% at BOTH charge levels.
THIS IS THE ABSOLUTE ONLY WAY TO TELL IF THE VEHCILE FULLY EXTENDED CHARGED!!!
When the battery is cold, the GOM will be significantly less. Also, in the future when battery degradation becomes noticeable, the values should be somewhat less. Sorry, I can only guess at those values.
The Mercedes dash consumption meter (miles per kWh) is calibrated so that 3.6 miles per kWh will show 3.0 on the dash. The correction factor is 83.7%, or 1.2.
The B-Class ED has a usable battery capacity of 28kWh in normal charge and 31.5kWh in extended charge.
To estimate ACTUAL range (not the GOM), you only need to charge it up and estimate the consumption rate. At 65mph on flat, dry roads without a headwind and no heater use, the car will consume 3.0 FROM START as indicated on the dash REGARDLESS OF WHAT THE GOM SAYS. Again, the only viable purpose of the GOM after a consumption meter reset is to indicate whether you have 28kWh or 31.5kWh with a full charge when the battery percent shows "100%".
3.0 miles/kWh dash value x 1.2 correction x 28 kWh = 100 mile real RANGE on a standard charge (GOM will show 86-88 miles after reset to indicate 28kWh).
3.0 miles/kWh dash value x 1.2 correction x 31.5 kWh = 113 mile range on an extended charge (GOM will show 93-95 miles after reset to indicate 31.5kWh (some 2014 model year cars do not have this extended charge feature).
If your weather conditions are worse than dry / warm / no wind / no elevation climb, or you're running the heater, or driving faster, the consumption rate that you experience will be lower, maybe 2.5 miles/kWh? You will have to determine this through careful experience of the "miles/kWh since start" and a simple math exercise outlined above.
Because the battery will also show in %, you can multiply that percent by 28kWh to estimate available kWh. Let's say it say 50%, which would be 14kWh. Therefore:
3.0 miles/kWh dash value x 1.2 correction x 14kWh = 50 mile range at 50% and 65mph down a flat, dry road without a heater.
Unfortunately, this trick doesn't add the additional miles for "extended" charge, since the meter will just show 100% from 28kWh stored to 31.5kWh. Yes, that seems dumb, except that as the battery ages and degrades, somewhere around 70% to 85% capacity (we don't know yet), the extended and normal charge will have the same kWh.
That's how they will attempt to hide the degradation over time. Not something to worry about with new-ish cars.
This GOM issue pops up OVER AND OVER, so I will just keep posting this same response. We had it with the LEAF and the Toyota RAV4 EV. Thankfully, Tesla uses "rated range", instead of a GOM, like everybody else.
