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It seems to me that the EV market is missing a key piece of information when you are looking for your next vehicle. For all ICE we have for years based our view of efficiency on MPG, but I can't find any such readily available indicator for EVs.

It's not hard to find the total WLTP range and the usable battery size to calculate miles per KWH, but can anyone point me to a single database that holds this for current EVs?
Its really easy to find range tables, but that is only half the story....
 

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I think this may come in a few years time, once people are comfortable with the overall range of EVs.
I doubt it because BEVs are so efficient (around 80%) in contrast to ICEs (around 20 to 30%) that the driving style has a huge impact on the variability of the miles per kWh that can be achieved. In contrast the ICE is so inefficient that the variability of the overall mpg is much less affected by driving style.
 

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It's well worth having a play on abetterrouteplanner.com. You can stick in your choice of Bev, select some typical tricky journey you might be worried about, and see what happens. E.g compare the Ioniq 38 kWh with the Kona 39 kWh - almost the same battery (not quite, I think the Ioniq has 1 or 2 fewer cells due to lack of space), bt the difference in range as you increase the average speed is very instructive! This website is supposed to use real user data, so should be a good indicator for you. Ioniq is very aerodynamic, while Kona & other Suv styles are more like a brick.
 

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although it starts with charging rate it does discuss efficiency in this context
 

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Its an interesting question and a bit of a conundrum - one that I have been trying to tackle in a pragmatic way with the 100% to 20% mileage log. This hopes to develop a real life log of actual miles travelled for 80% of the battery capacity for a number of vehicles. Easy then to convert to miles per kWh for each vehicle type so that for my 40kWh Nissan Leaf, I might travel 115 miles for 32kWh* ie about 3.6 miles per kWh. So far unfortunately only populated by me and a few others.

But what also matters, and probably matters more, is the cost of electricity per mile travelled. For an ICE, there are small regional differences in fuel costs and a consistent difference between diesel and petrol but for a BEV you might do all your charging at home, but this could be 5p per unit up to 20p or you might get all your power free at pod point or Nissan dealership or you could be paying 39p per unit if you are unlucky. How odd it would be if we had the same range of costs with petrol. So going back to my example, the least I might pay is 1.4p per mile and a maximum of nearly 11p per mile.

So come on you regulars, with your I-Pace, i3, egolf, Teslas, MG, Kona, Niro, start putting some real data into the log - https://www.speakev.com/threads/the-100-to-20-mileage-log.135856/post-2711638

I have a feeling that in reality, and more or less as it is for ICE cars, the efficiency of a standard family hatch or saloon will not vary very much. Luxury barges will be inefficient and small city cars might get slightly improved efficiency. I really hanker over an electric Rover 75 which I suspect would be relatively inefficient but still better than the v6 petrol version?



* This is kWh of battery capacity so probably up to 10% less than kWh charging energy.
 

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Sorry but i think this is a little bit meaningless.
In my experience there are too many variables, in descending order,


Speed of travel can effct range by a ratio of 2 to 1
Temp affecting capacity of battery
Amount of heating used, even more noticable on short journeys as the cabin takes time to get up to temp and the heater to throttle back.
Wind direction, the difference between wind on the front to that from behind. Even the lightest of breezes can be detected by my E-Golf and can easily amount to 10% difference in a breeze.
A one off amount of potential energy difference between start and end of journey.
Agressive driving where the motor is operating outside the range of max efficiency.

Overall the difference in conditions can easily make a total difference of 2.5 to 1 thus degating anymeanfull results.

Sorry.
 

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No need to be sorry. You are right in all you say. But that is the very reason we need a log of real life figures. The factors you mention affecting efficiency in the most part relate to ICE vehicles too yet we often discuss mpg for different models both official figures and those we collect ourselves. My rover did 16 mpg for short journeys in winter yet 35mpg on a long run at legal motorway speeds.
 

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As Bjorn's wonderful video showed. It's not just about battery size, efficiency. Charging speed in combination with efficiency is also very important.

He concluded by saying 1000 km challenge is a good indication of the vehicle capabilities. I've been saying the same thing for over 1 year now, we need to have a standard way to compare EV's by their time to do a long distance that includes multiple charging.

Single datapoints for range, efficiency, charging speed or battery size does not tell the whole story and difficult to compare. The above "time to do 1000 km" is a very simple figure to allow comparison, yet combines all factors.
 

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"Time to do 1000km" is not a figure that combines all we need to know about an EVs performance. You still need to know range and charging speed separately. Most people will very rarely drive 1000km without a break or with a tight time constraint.
 

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"Time to do 1000km" is not a figure that combines all we need to know about an EVs performance. You still need to know range and charging speed separately. Most people will very rarely drive 1000km without a break or with a tight time constraint.
Of course no manufacturer will only publish a single number. You'll still get all other information.

But if there were a standardised "time to do 1000km" figure, it would make it much easier to compare capabilities of all EV's. No need to research whether the car rapidgates, or find out later the car is very inefficient with low mph charging speed.

Would be also good to get stats of their testing, eg. to get their ideal time, at what percentage did they start rapid charging and stopped at what percentage. In form of a battery percentage graph throughout the 1000km. This will give you idea of battery headroom (eg. E-Tron vs Tesla) and battery ideal charging range.



Another useful figure is efficiency at low temperature and short range. A typical use-case for commuter in winter. For example, the car is tested with ambient temperature of 5c, battery cooled down to 10c. Test starts with 15min of preheating to 22c followed by 30min of driving at stop/start city up to 30mph for 10 miles. Quote energy used.
 

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@wyx087 What you say is correct but very few people travel 1000km so many drivers will not find it particularly useful. As I mentioned, it would be really helpful if there were many more contributions to the 100% to 20% range log I started. There are enough owners here to put together some really interesting real world data which in a way takes account of all the variables by averaging multiple records for each car.
 

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@wyx087 What you say is correct but very few people travel 1000km so many drivers will not find it particularly useful. As I mentioned, it would be really helpful if there were many more contributions to the 100% to 20% range log I started. There are enough owners here to put together some really interesting real world data which in a way takes account of all the variables by averaging multiple records for each car.
Oh dear! Life is so complicated, 100% to 20% is only the indicated relative battery percentage that is shown to the user. The actual 100% and 20% absolute levels will be different depending on how the BMS in each car goes about its job.

So 100% to 20% is not a level playing field basis for comparing efficiency.
 

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I completely understand that point but the idea was to collect real life range data quickly and easily. The basis of this is that many people charge to 100% overnight and it would not be reasonable to run down to empty just to collect data. I usually use 20% capacity when calculating how far I can comfortably go before charging. It's meant to be a broad brush comparison of different cars in terms of range, not an exacting measure of efficiency. Converting the 100% to 20% to kWh will never be precise for the reasons you give but there may be something to be gained by at least attempting it.
 
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