How can I keep track of mileage/efficiency?

How can I keep track of mileage/efficiency?

I've been keeping track of my mileage (miles/gallon) on my X1 and comparing it to the onboard computer and the EPA rating. How would I do this with the M3?

1. I plan on installing a 14-50 outlet and using it to charge the car every few days (I'm retired and I don't drive much). Does the Tesla onboard computer show how many KWH were delivered to the battery? How would I determine the charging losses (I've heard that they're 10-12%)?

2. If I charge at a Supercharger does it show the KWH added after I disconnect the plug?

Thanks in advance,


stevenmaifert | 27 augustus 2017

Cliff - I don't know if the info is available on the M3, but there is a setting for the MS that will tell you how many kWh were delivered during a charging session, both with a Level 2 NEMA 14-50/HPWC charge and when you Level 3 Supercharge. My hunch would be the M3 will have that too. The car does not accumulate so you would have to record kWh received during each charging session manually on a spreadsheet. Trying to measure losses during a charging session is tricky and I will leave that to more knowledgeable folks to try and explain. Using the MS again, there is an A and a B trip meter that will show miles driven, kWh consumed and wH per mile efficiency. If there is a B meter on the M3, never reset it and it will show you the overall electric fuel efficiency during the life of the car. What it doesn't do is compare the kWh received during charging and compare that with the kWh consumed.

All that said, unlike an ICE car and gasoline, the M3 will consume electricity just sitting idle in your garage. We call that the "Vampire Drain" as the car is never totally "off". The MS has a feature called the "Sleep" mode which takes the cars computers down to a lower state of readiness which reduces the idle consumption but then the car takes a few moments more to be ready to go when you start it. Connecting with the car remotely with the smartphone app also causes the car to "wake up" which uses a very small amount of charge.

Tâm | 27 augustus 2017

1) show how many KWH were delivered to the battery?


Only if you don't disrupt the cable connection. When it detects cable disconnection, that info is reset to zero on your screen.

2) How would I determine the charging losses (I've heard that they're 10-12%)?

Your car has all those info and more but you need to be a programmer to bring them out.

Otherwise, you might consider to pay for third party monitoring system like:

It shows like:

16.5/18.1kWh 91% eff. 242V 20A 90/90% Charging

That means your battery got 16.5 kWh in, but it actually pay your electric company 18.1 kWh due to inefficiency (heat, wire length/size...)

Notice: Third party car loggers are approved by Tesla and we don't know who they are so you pay them with your own risk (Tesla could block them out at any time if they want to).

2. If I charge at a Supercharger does it show the KWH added after I disconnect the plug?


Remember question #1. Do not disrupt the cable connection if you want to read the kWh added.

Tâm | 27 augustus 2017

Sorry, typo: It should say:

Notice: Third party car loggers are NOT approved by Tesla and we don't know who they are so you pay them with your own risk (Tesla could block them out at any time if they want to).

bj | 27 augustus 2017

"How can I keep track of mileage/efficiency?" - you could buy a Nissan Leaf, which records all of this data and sends it to the Nissan Connect server. The owner can then download the data (previous 6 months is kept) and spreadsheet it to your heart's content. I find the data fascinating and it tells me all sorts of interesting things.

Obviously that doesn't help you with a Tesla though. I am stunned that Tesla do not (yet?) offer a similar telematics capability to the Leaf, given Tesla's otherwise excellent credentials in connectedness/OTA updates/cloud-ification. It seems a bizarre omission.

Tâm | 27 augustus 2017


My guess: Too many things on Tesla's plate so it is not a priority because you can still pay a third party car logger to do it for you if you don't know how to code.

deemo | 27 augustus 2017

On a Model S, there are 4 trip computers that keep track of Watts/Mile average and KwH used. There are 2 user set (I have one set to day first picked car up) and 2 Automatic - since last charge and current trip. The inverse of watt/ mile is miles /Kw (250W/Mi = 4 Mi/Kw). I hope M3 has these also.

BTW I have a Leaf and the Tesla has more info.

bj | 28 augustus 2017

@Tâm - well maybe but as you point out, third party loggers are not approved and might get blocked.

@deemo - the Leaf trip computer does that too (averages of various things since the computer was last reset) but that is dfferent to recording every trip detail (every time you turn the car on until you turn it off is a "trip"). Does Telsa record kWh used, kWh regeneration, trip distance, trip duration? If so how does a Telsa owner obtain that data?

Robocheme | 28 augustus 2017

Thank you for all of the replies.

@Tâm, I had a question about your example. How would it know or calculate the 18.1 kWH that is received from the electric company? It seems like you'd need a meter at the breaker or is it based on some set efficiency (91%) applied to the 16.5 kWh?

Thanks again,

deemo | 28 augustus 2017

Tesla Model S displays average W/Mi, distance, duration and total kWh used for the data sets - it is available on the main display inside the car and most of it can be put on the drivers display also. In many ways very similar to the Leaf but more granular and on 1 display instead of having to scroll. Also the data is down to the watt i.e. 298 w/mi rather than the rounding the Leaf does on the drivers display of 3.8 mi/Kw. In my opinion, the Tesla with 4 sets of data vs 1 in the Leaf gives much more live data to the driver without needing to go into a downloaded log and analyze. The leaf does have a use history in car but pretty limited in scope.

bj | 28 augustus 2017

@deemo - so you confirm that Telsa does not record per-trip data in user-accessible form, or kWh regeneration data. Thank you.

Yes it is manual for the Leaf owner to extract the detailed data (although you can have a monthly summary automatically emailed to you), but so it is too with Tesla - either manual logging (yuk) or using a third party logger. Using the server data I can calculate Leaf efficiency to an arbitrary number of decimal points (OK, within the resolution of the kWh and km distance data logging), even though on screen in the car it shows it to 2 decimal points only.

The Leaf records a lot of data - look at the back of the Leaf Owners manual for the exact list of what it records and sends to the Nissan server - there are about 60 parameters. Tesla presumably want to know what their fleet is doing and learn a lot about BEV performance, usage and charging behaviour so you'd think they would want to record similar data, they just don't make it accessible to the owner for some reason.