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Discussion Starter #1
Hi folks,

I did a test drive in a DS3 Crossback e-tense and I loved it.

In the energy info it says:

Electric Energy Consumption : 3.5 Miles/KWh

This is what I do not really understand, I know in my Merc I can get a good 60mpg but what does this mean above? Is the higher the number better or lower?

I am a noob to the EV world so apologies if this is a really basic question. I did try and Google it but couldn't find any real info even on Zap-Map.

Here is a pic of energy info:

127270




Thank you for the advice in advance, looking forward to being an EV driver soon :)

Ben.
 

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More miles per kWh means better cost per mile. Providing you know how much you're paying per kWh it's pretty straightforward to calculate actual cost per mile.
 

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as per mpg (miles per gallon) , a higher figure is better. 3.5 miles/kwh is about typical for an EV.

The e-tense battery has around 47kwh of usable energy.

thus 47*3.5 will give you about 164miles of range.

High speed motorway driving in winter you might get down to 3miles/kwh, and thus your range would drop to 47*3 = 141miles
 

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The miles per kWh will vary depending on outside temperature and driving style, but I've just done a calculation and I think your Merc is doing about 3/4 of a mile per kWh.
If I've worked it out correctly the EV is about 4.6 times more efficient so roughly equivalent to 265 mpg.

Most of this is due to the ineffiency of ICE, only 25 to 30% of the fuel is used move the car, the rest is wasted in heat and friction.

But I'm sure someone will come along with more accurate figures soon
 

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The miles per kWh will vary depending on outside temperature and driving style, but I've just done a calculation and I think your Merc is doing about 3/4 of a mile per kWh.
If I've worked it out correctly the EV is about 4.6 times more efficient so roughly equivalent to 265 mpg.
A litre of diesel is around 11kwh, so a gallon is around 50kwh.
Thus 60mpg is around 1.2 miles per kwh.
 

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As I said it was a quick calculation, the figure I found was 9kWh per litre.

So the on the figure you found would make the Citroen about 174 mpg.

It all goes to show how brilliant the efficiency of EVs is. (y)
 

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Discussion Starter #7
Oh wow, thank you, everyone, for the amazing answers! When we were on the test drive, the range stayed at 87 miles of range and never moved. We did about 45 minutes of driving, some fast (motorway 80mph) and then slow driving (city 20mph). Then I did some driving in eco, normal and sport but the mileage never moved once.

I asked the chap from DS why and he said that is was a new car and the team members had been out driving it a little fast so the milage calculation would need to update.

Would this be true of most EV cars?

Thank you again, I am very excited to drive EV and get rid of my diesel merc.
 

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Oh wow, thank you, everyone, for the amazing answers! When we were on the test drive, the range stayed at 87 miles of range and never moved. We did about 45 minutes of driving, some fast (motorway 80mph) and then slow driving (city 20mph). Then I did some driving in eco, normal and sport but the mileage never moved once.

I asked the chap from DS why and he said that is was a new car and the team members had been out driving it a little fast so the milage calculation would need to update.

Would this be true of most EV cars?

Thank you again, I am very excited to drive EV and get rid of my diesel merc.
Yes, the remaining range reflects the recent miles/ kWh figure, which directly corresponds to the recent driving style.
 

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Discussion Starter #9
So if the staff didn't speed around in it beforehand I would have a better understanding of the mileage - ha car garage staff. Thanks for the help everyone. Are there more good guides on this forum I can educate myself on EV speak etc etc - cheers!
 

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Out-of-interest, does anyone have a link to the test criteria used to determine miles/kWh? Experienced EV owners know that what is shown on the sheet in the OP's post is about as meaningful as mpg shown for new cars.
 

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Oh wow, thank you, everyone, for the amazing answers! When we were on the test drive, the range stayed at 87 miles of range and never moved. We did about 45 minutes of driving, some fast (motorway 80mph) and then slow driving (city 20mph). Then I did some driving in eco, normal and sport but the mileage never moved once.

I asked the chap from DS why and he said that is was a new car and the team members had been out driving it a little fast so the milage calculation would need to update.

Would this be true of most EV cars?

Thank you again, I am very excited to drive EV and get rid of my diesel merc.
The range remaining indication shown all all EVs is at best a calculated guess based on previous trips (distance and speed); road/weather conditions; driver profiles and use of auxiliary items such as light; wipers and heating. This is why the display goes by the generic acronym of GOM - Guess'o' Meter. With respect, you are displaying the classic symptoms of new/potential owner range anxiety. The same factors pertain to all cars; however, with a 600 mile plus tank and many filling stations nobody worries about it.

I drive a BMW i3 which has a range in the summer of about 190 miles at c.20C when driven at an average speed of 60mph with a light foot and as much coasting as possible. In the Winter, this range can drop to c.140 miles in cold and wet conditions. If you are 'hell bent' on driving at 80mph on a motorway then an EV may not be for you. Simple maths: if the drag at 40 mph is X, then the drag at 80mph is 4X. Similarly, if you are fast into roundabouts and junctions, then you will miss out on the positives associated with regenerative braking and coasting. The latter saves more miles than regenerative braking.
 

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Discussion Starter #13
It was really quite special to be honest, the first time I've driven electric. The chap who works at DS said we could drive anywhere and no time pressure which was really great. Lots of mixed driving, motorway, town, city and A roads. Did all manner of driving, fast, slow & stop/start. I love the electric motor drive, it is actually addictive. I also felt really calm driving electric, no noisy engine upfront when stopped or making decisions on pulling out etc.

After we tested this car we had a great drive in a Kia E-niro which was also really amazing but I didn't like the regen as much but I did love that you can change it with the flappy paddles. I found I was using the paddles to slow the car down rather than the brakes ha!

So thank you for asking @Todor - I literally can not wait to become a full EV driver but have to wait until April now. Order in, just a waiting game. Does anyone know about EVs in the park in Coventry - I might attend this year :)
 

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A litre of diesel is around 11kwh, so a gallon is around 50kwh.
Thus 60mpg is around 1.2 miles per kwh.
Yep. Some useful rules-of-thumb to remember:
  • 45mpg ≈ 10 miles per litre
  • 1 litre of petrol or diesel ≈ 10kWh of released heat energy
  • so 45mpg ≈ 1 mile per kWh
A typical small-ish EV's 4 miles per kWh just demonstrates how inefficient ICE engines are: 90mpg is virtually unthinkable in a pure-ICE car, but the EV is twice as good as that again.

The downside is battery energy density, which currently peaks at about 2.5MJ per litre (battery volume). Diesel is roughly 40MJ/litre, approx sixteen times better, but ICE efficiency is roughly four times worse. So to get equivalent "range density" (miles per litre of package space used by fuel tank or battery), battery tech has to improve roughly fourfold to match fossil fuels.
 

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...Similarly, if you are fast into roundabouts and junctions, then you will miss out on the positives associated with regenerative braking and coasting. The latter saves more miles than regenerative braking.
Actually, it's significantly more economical to avoid having to accelerate again by maintaining as much speed through corners and junctions as possible (to a point as energy is wasted when changing direction). Accelerating is where most EV energy is expended. As you go faster you have to accelerate more to counteract the air resistance and friction with the road, but (aside from reduced drag) there is nothing to be gained from slowing down. There is a common misconception that more regenerative braking gives you greater range and that's why city driving is more efficient. The truth is that it is entirely due to the reduction in friction that comes with lower speeds.
 

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Discussion Starter #17
These replies just keep getting better and better. Starting to also learn about public charging too :)
 

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The cost of recharging is also "variable"! I try to do as much of my recharging on sunny days when my 4kW solar panel array is exporting leccy. The slowest an EV can be charged is 6A, call it 1.5 kW. So If I'm exporting more than that at any time, then plugging my EV in means I'm getting free miles! Apart from tyre wear that is, which is somewhere from 1 to 2 p/mile-ish. Domestic charging at say 18p per kWh (Unit) means it costs me appx 4p/mile, but some like to charge overnight on Economy /similar which can be far cheaper! And then you might be on a long trip somewhere, forced to use one of the latest Rapid chargers at about 70p per kWh ! More expensive than patrol !! Ouch.
 

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Discussion Starter #19
So, I am with British Gas and our rate is 14.5 kwh day and night - how can I convert this into pence per mile? Cheers!
 
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