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Guess-O-Meter or Accurate Range Display?

3557 Views 21 Replies 13 Participants Last post by  Palouser
I see some refer to the Volts range display as a Guess-O-Meter (GOM). My range display is pretty darn accurate, so why do some refer to theirs as a "GOM"?

I suspect the issue is based on the driver not understanding (or forgetting) things that affect car range. The car's range display is based on the drivers last few trips, and it is basically saying, "Based on the last few days of driving, you should get this range, all things being equal."

That last part is important, if conditions change, the estimated range will be off. This is where people get tripped up.

Changes in condition include:
  • Tire Pressure. Low tire pressure will decrease range. It's very easy to loose 2-3 or more PSI when the outside air temps drop.
  • Weather. Cold, wet, snow will all decrease range.
  • Heater/A/C. Cranking these up will decrease range.
  • Aggressive Driving. The more aggressive the driver is in starts and stops, the more the range will be negatively affected.
  • Speed. Speed kills ...battery range. The faster you drive the more it will negatively affect the battery range.
The effective range of the car can drop (or increase) based on changes in the above compared to the previous days driving record. I think some people forget that, leading to calling the range display as GOM.
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Yes, I forgot another variable, Terrain (how hilly or flat your daily drive is) will also affect the miles. Also the shorthand of saying it's based on your last few days driving may actually be referring to the last 5 charge cycles based on some older threads. If so, driving 4 days may not affect the range display unless each day resulted in a full recharge at the end of each day. I wish WOT were around to clarify.
Mine is not particularly accurate. Part of it is the climate, here, especially this time of year. One drive you need heat, the next some air-con, the next no climate control. Also, my driving varies between short trips to those using the entire battery. Except for the rare bursts of acceleration, my driving style is probably the most consistent thing about how the car is used.
Right. Hard for any thing or anyone to be accurate when the conditions keep changing. Most gas cars don't even try (maybe some new ones do?), they simply tell you how full the gas tank is. It's up to the driver to make the range estimate. You can do the same with the Volt of course. Just look at the battery bars and try to figure it out yourself. :)
You could say the range is accurate looking backwards, but going forward there are changes in driving technique, speed, weather, etc. that require the computer to make ongoing changes, or guesses, for your total mileage on a given charge.
Yup, when the underlying conditions are changing compared to what was happening in previous drives, making an accurate long term estimate is not going to happen. I think the car does a reasonably good job of predicting the miles at the start of the day based on recent drives. If you drive like you have been, all is well. But all you need to do is, say turn heat and fan on full blast and drive at 80 MPH (assuming on previous drives you were not doing neither) to invalidate the estimate. I don't blame that range miss on the car. As the driver, you know you've changed the rules of the game and should expect less miles from the battery as a result.
I'm not a Tesla fanboy but I think Tesla's range is a lot more accurate especially if you enter your destination. It's calculating more than historic trends to estimate range. However I don't own one so I would be parroting other Testa reviewers. I heard they're even taking temperature, elevation, traffic, speed limit, vehicle load and probably other variables I haven't even thought about into account.
IF the car knows WHERE you are going and THE ROUTE you will be taking, it seems reasonable to have the car take these current factors into consideration when estimating range. Of course this assumes every trip you make would need to start by powering up and entering the destination and route.

I suspect many will not do this except maybe for very long trips (vacation, etc.).
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