Discussion
I am not aware of a site which will do the calculation for you, but if you look at this website:
https://ev-database.org/uk/
for each model there is a "real energy consumption" section which gives estimated consumption for highway (i.e.70 mph) in cold (minus 10C) and ideal (23C) conditions. If your journey is 90% motorway that will be close enough. You just need to multiply the consumption figure by the distance (70 in your case) and then multiply the result by your cost of electricity. You should then add another 15% or so to allow for charging losses, as not all the electricity you take from the grid ends up in the battery.
https://ev-database.org/uk/
for each model there is a "real energy consumption" section which gives estimated consumption for highway (i.e.70 mph) in cold (minus 10C) and ideal (23C) conditions. If your journey is 90% motorway that will be close enough. You just need to multiply the consumption figure by the distance (70 in your case) and then multiply the result by your cost of electricity. You should then add another 15% or so to allow for charging losses, as not all the electricity you take from the grid ends up in the battery.
You need to know how much you are paying per kWh.
Then, just look at the miles/kWh for whichever EV you are looking at. EV database has this info.
If the EV does 3 miles/kWh, then 70 / 3 = 23.33kWh.
If you pay 28p/kWh, then 23.33 x 28p = £6.53 cost.
If you pay 7p/kWh, then 23.33 x 7p = £1.63.
You can add on 10% for charging loses due to heat so an additional 65p or 16p to the above costs.
Then, just look at the miles/kWh for whichever EV you are looking at. EV database has this info.
If the EV does 3 miles/kWh, then 70 / 3 = 23.33kWh.
If you pay 28p/kWh, then 23.33 x 28p = £6.53 cost.
If you pay 7p/kWh, then 23.33 x 7p = £1.63.
You can add on 10% for charging loses due to heat so an additional 65p or 16p to the above costs.
Pretty much what they said.
To be honest it probably doesn't make much sense to focus on one specific EV but then to look for 'average' values for driving style, temperature and electricity cost. This is because the variation between EVs efficiency in motorway conditions is probably much less than the variations in the other factors. I.e. driving the most efficient EV, an Ioniq, but paying £1/kWh for public charging, would be far more expensive than driving an amp-eater like an I-Pace, but charging it at home at 7p/kWh on Intelligent Octopus Go.
Worked example:
1) Motorway Energy efficiency in miles/kWh. The simple thing is to assume 3 as it'll be roughly correct for the vast majority of EVs. If you want a better estimate, go to the EV Database and look at 'Real Energy Consumption'.
For instance, my Polestar 2 LRDM MY22:
https://ev-database.org/uk/car/1488/Polestar-2-Lon...
This lists Highway - Cold Weather of 429 Wh/mile, and Highway - Mild Weather as 333 Wh/mile.
Take a simple average of both for year-round use give 381 Wh/mile.
Divide 1000 by 381 gives 2.63 miles/kWh.
70 divided by 2.63 gives 26.6 kWh used.
2) Energy Cost
An 'average' value would be the current price cap of approximately 26p / kWh. 26p x 26.6 kWh gives about £6.91 total cost.
For me on Intelligent Octopus Go at 7p/kWh, that would be £1.86
At a public charger it could be as much as £26.60 if paying £1/kWh.
To do this yourself, look up the EV you're interested in in the EV database above to get the Highway consumption figures. Then take your electricity cost from your latest bill, or the tariff you think you'd move onto, to get the cost.
To be honest it probably doesn't make much sense to focus on one specific EV but then to look for 'average' values for driving style, temperature and electricity cost. This is because the variation between EVs efficiency in motorway conditions is probably much less than the variations in the other factors. I.e. driving the most efficient EV, an Ioniq, but paying £1/kWh for public charging, would be far more expensive than driving an amp-eater like an I-Pace, but charging it at home at 7p/kWh on Intelligent Octopus Go.
Worked example:
1) Motorway Energy efficiency in miles/kWh. The simple thing is to assume 3 as it'll be roughly correct for the vast majority of EVs. If you want a better estimate, go to the EV Database and look at 'Real Energy Consumption'.
For instance, my Polestar 2 LRDM MY22:
https://ev-database.org/uk/car/1488/Polestar-2-Lon...
This lists Highway - Cold Weather of 429 Wh/mile, and Highway - Mild Weather as 333 Wh/mile.
Take a simple average of both for year-round use give 381 Wh/mile.
Divide 1000 by 381 gives 2.63 miles/kWh.
70 divided by 2.63 gives 26.6 kWh used.
2) Energy Cost
An 'average' value would be the current price cap of approximately 26p / kWh. 26p x 26.6 kWh gives about £6.91 total cost.
For me on Intelligent Octopus Go at 7p/kWh, that would be £1.86
At a public charger it could be as much as £26.60 if paying £1/kWh.
To do this yourself, look up the EV you're interested in in the EV database above to get the Highway consumption figures. Then take your electricity cost from your latest bill, or the tariff you think you'd move onto, to get the cost.
Edited by samoht on Thursday 12th February 17:08
teeceeee said:
is there an online calculator anywhere that can work out approx costs of a 70 mile return commute (90% motorway) for a specific EV.
I know there are a lot of variables in both cost to charge and 'consumption' but am just looking for 'average' numbers - not specifics if possible.
There's no calculator because it's near impossible to know but I do roughly what you are doing. I know there are a lot of variables in both cost to charge and 'consumption' but am just looking for 'average' numbers - not specifics if possible.
On the cheap Octopus tariff 7p and I use say around 19KW in my Tesla M3LR it's about £1.33.
On the standard rate 27p it's £5.13.
Looking back at my bill, on the cheap rate it costs me £1.40-£1.60 a night, that's because I use other things while it is charging.
I spend most of my time on the motorway, sat anywhere between 60mph to 70mph. Then the usual traffic as I get close to the city. I don't drive fast because what's the point? I'd save maybe 2 minutes at best.
teeceeee said:
is there an online calculator anywhere that can work out approx costs of a 70 mile return commute (90% motorway) for a specific EV.
I know there are a lot of variables in both cost to charge and 'consumption' but am just looking for 'average' numbers - not specifics if possible.
You don't need a calculator. I know there are a lot of variables in both cost to charge and 'consumption' but am just looking for 'average' numbers - not specifics if possible.
(70/3) x 0.07
That's your ballpark fuel cost per day.
...plus 3p/mile from Apr 28.
If you do go for it, keep an eye on Octopus Drive Pack - they're not taking on new customers for it at the moment, but at £30 it'd be a good deal. Daughter managed to get on it at launch when they did it for £20. She does 65 mile round trip, mostly motorway, in a Gen2 Kona. I dread to think what the car is doing per kWh - she's always been a "press on" driver and the interior gets a good blasting before setting off each way. Also the fixed price means charging losses don't matter.
If you do go for it, keep an eye on Octopus Drive Pack - they're not taking on new customers for it at the moment, but at £30 it'd be a good deal. Daughter managed to get on it at launch when they did it for £20. She does 65 mile round trip, mostly motorway, in a Gen2 Kona. I dread to think what the car is doing per kWh - she's always been a "press on" driver and the interior gets a good blasting before setting off each way. Also the fixed price means charging losses don't matter.
kambites said:
Sheepshanks said:
...plus 3p/mile from Apr 28.
The way they've been rowing back on things recently, this government having announced something as policy probably makes it slightly less likely that it will actually happen. 
I picked up a Polestar 2 LRDM MY2022 a couple of weeks ago, 1st week I did 291 miles (mainly motorway miles to work and back) averaged 33.6 kWh/100 miles so approx 3m /kWh.
I pay 6.5p kWh with Eon on the over night charge rate so roughly 2.18p/mile against 15p/mile in my 2019 V90 D4 engine (yes I'm a knob who likes a spreadsheet!)
I think I'll be using public chargers for longer journeys around 6 times a year so an EV makes sense for my driving needs.
I also have doubts about the 3p/mile excess charge ever happening TBH.
I pay 6.5p kWh with Eon on the over night charge rate so roughly 2.18p/mile against 15p/mile in my 2019 V90 D4 engine (yes I'm a knob who likes a spreadsheet!)
I think I'll be using public chargers for longer journeys around 6 times a year so an EV makes sense for my driving needs.
I also have doubts about the 3p/mile excess charge ever happening TBH.
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