Can someone check my man-maths petrol and electric
Can someone check my man-maths petrol and electric
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Pistonheader101

Original Poster:

2,206 posts

138 months

Sunday 12th June 2022
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From october elec is rising 32%, so our tarrif will be 38p per KwH.

The i3 battery is 34kWh that gives around 80 miles range in perfect conditions. This equates to £12.92 to get 80 miles.

assume petrol is £2.00 for october. a car giving 56mpg will therefore cost £12.99 to get 80 miles.


Does this math add up in theory?

PomBstard

7,930 posts

273 months

Sunday 12th June 2022
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Man Maths requires an aim, a preferred end point, in order to be properly successful.

Do you want to keep the i3, or would you prefer a petrol car? This is the crux to your issue.

Otherwise, it’s just basic economics, and that’s not really what Man Maths is about.

wisbech

4,385 posts

152 months

Sunday 12th June 2022
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Well, the maths is right.

Good luck getting 56mpg consistently though - I have a 1.8L Corolla Hybrid, and get about 51-53 mpg (brimming tank method, but 91 RON fuel and mostly town driving)

Also, are you sure that is an 80 mile range full to empty? Or are you keeping 20% or so for range anxiety? 80 miles would be 30kw/100km, which is about 50% worse than it's official rating

SS2.

14,712 posts

269 months

Sunday 12th June 2022
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How accurate do you need your man maths to be ?

For instance, you won't get 24kWh of available EV power by putting in 24kWh of charge - it's more likely to require upwards pf 27kWh.

hepy

1,367 posts

171 months

Sunday 12th June 2022
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Can you switch to a provider that offers a cheaper overnight rate, then charging will be cheaper?

Sorry, not man maths but practicality.

deggles

731 posts

233 months

Sunday 12th June 2022
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Not really, electricity price is likely to go up by more than 32% in October, you're also assuming 100% charging efficiency, I'd have thought a 34kWh battery needs nearer 40kWh to charge.

P. ONeill

1,455 posts

83 months

Sunday 12th June 2022
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If petrol was a tenner a litre I still wouldn’t think about an i3 or an ID4 or whatever. Nothing to do with man maths, I just couldn’t.

motco

17,662 posts

277 months

Sunday 12th June 2022
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A Nissan Leaf drives between 5 and 3 miles per kWh dependent on conditions, heater use, etc. So it will, at 38p/kWh cost between 7.6 and 12.7p per mile. Over 80 miles that's £10 max and £6 min

Good luck with 56mpg! It's likely to be nearer 40mpg and that will cost 22p/mile or over 80 miles £18

At the moment it costs 1/3 as much to drive a Leaf as a 2.2l diesel in the real world. Assuming home charging that is.

Norton850

852 posts

68 months

Sunday 12th June 2022
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P. ONeill said:
If petrol was a tenner a litre I still wouldn’t think about an i3 or an ID4 or whatever. Nothing to do with man maths, I just couldn’t.
I thought the same so bought a Phev which gives me enough range on electric only to get to work where i charge for free.I haven't put any fuel in it since pick up a month ago.

But i am looking into getting a newish ev for wife after test driving a i3,these things a great fun.

Scrimpton

12,959 posts

268 months

Sunday 12th June 2022
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I thought the I3 was quite efficient, my 38kwh Ioniq is doing well over 160 miles on a charge at the moment.

Pistonheader101

Original Poster:

2,206 posts

138 months

Sunday 12th June 2022
quotequote all
Thanks all.

I’m in the process of buying a new car and thinking very much of the bmw i3.

I bought a Range Rover sport but due to delays it just hasn’t arrived yet, so will be cancelling it.

Was thinking of a petrol hybrid with higher mpg but maybe the i3 Rex is a good idea instead?

Norton850

852 posts

68 months

Sunday 12th June 2022
quotequote all
motco said:
A Nissan Leaf drives between 5 and 3 miles per kWh dependent on conditions, heater use, etc. So it will, at 38p/kWh cost between 7.6 and 12.7p per mile. Over 80 miles that's £10 max and £6 min

Good luck with 56mpg! It's likely to be nearer 40mpg and that will cost 22p/mile or over 80 miles £18

At the moment it costs 1/3 as much to drive a Leaf as a 2.2l diesel in the real world. Assuming home charging that is.
Depends on the car,our pool cars (Aygo and Yaris) both average approx 55mpg for our commute or just pootling around locally,ok both small cars but there are a few hybrid larger cars that can do 56mpg including our old Auris.

motco

17,662 posts

277 months

Sunday 12th June 2022
quotequote all
Norton850 said:
motco said:
A Nissan Leaf drives between 5 and 3 miles per kWh dependent on conditions, heater use, etc. So it will, at 38p/kWh cost between 7.6 and 12.7p per mile. Over 80 miles that's £10 max and £6 min

Good luck with 56mpg! It's likely to be nearer 40mpg and that will cost 22p/mile or over 80 miles £18

At the moment it costs 1/3 as much to drive a Leaf as a 2.2l diesel in the real world. Assuming home charging that is.
Depends on the car,our pool cars (Aygo and Yaris) both average approx 55mpg for our commute or just pootling around locally,ok both small cars but there are a few hybrid larger cars that can do 56mpg including our old Auris.
Of course, but the point is made that EV is and was much cheaper on fuel and very much cheaper on VED and servicing incidentally. The i3 is old now, I'd look at something from Kia or Hyundai personally.

plfrench

5,012 posts

299 months

Sunday 12th June 2022
quotequote all
Pistonheader101 said:
From october elec is rising 32%, so our tarrif will be 38p per KwH.

The i3 battery is 34kWh that gives around 80 miles range in perfect conditions. This equates to £12.92 to get 80 miles.

assume petrol is £2.00 for october. a car giving 56mpg will therefore cost £12.99 to get 80 miles.


Does this math add up in theory?
The thing that sticks out is your i3's efficiency. If it's using 34kWh to do 80 miles, that's 2.35 mi/kWh which is horrendously bad. You mention perfect conditions, but I'd expect better than that in the middle of winter at motorway speed.

My wife's e-golf which is heavier and a compromised design being built off a shared petrol / diesel platform has averaged 4.2 mi/kWh over the last 2300 miles according to the app. This is a good mix of motorway driving and me (which always hammers the range). With normal driving, high fours is easily achieved. Her last trip yesterday over a mix of urban, 50, & 60 mph roads averaged 4.6 mi/kWh over 23 miles. That would have chopped your cost in half.

Ignoring cost though, electric is just so much nicer to drive than your average ICE car. I'd pay more to drive electric daily - hene me paying for an early termination on my E350d to get into an EV... just need the car to arrive biggrin

Catnip64

217 posts

130 months

Sunday 12th June 2022
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The i3 battery is either 22, 33 or 44kWh, summer range is usually 80 miles with 22kWh, so which one do you have? This may affect the man-maths.....

Pistonheader101

Original Poster:

2,206 posts

138 months

Sunday 12th June 2022
quotequote all
Catnip64 said:
The i3 battery is either 22, 33 or 44kWh, summer range is usually 80 miles with 22kWh, so which one do you have? This may affect the man-maths.....
I would be looking at the 33 kWh one

Numpty with honours

218 posts

114 months

Sunday 12th June 2022
quotequote all
The servicing costs on an EV will be better than ICE

What is there to do on an EV car ? - change the coolant on around the motor, check the geometry of the wheels and glance at the brake pads, knowing that in reality with regenerative braking they're good for 100,000 miles.


ChocolateFrog

34,954 posts

204 months

Sunday 12th June 2022
quotequote all
deggles said:
Not really, electricity price is likely to go up by more than 32% in October, you're also assuming 100% charging efficiency, I'd have thought a 34kWh battery needs nearer 40kWh to charge.
I'd be a bit surprised if it was that bad but slow charging can't be that inefficient can it?

To the OP electricity prices are likely to come down again. Maybe not as cheap as they were but they won't stay at 40p per unit past next year IMO. Fuel is unlikely to come down much now. I'd be surprised if we see sub £1.50 p/l again.

lost in espace

6,620 posts

238 months

Sunday 12th June 2022
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OP get yourself on Octopus Go or Go Faster asap.

samoht

7,317 posts

177 months

Sunday 12th June 2022
quotequote all
lost in espace said:
OP get yourself on Octopus Go or Go Faster asap.
https://octopus.energy/go/rates/

You pay 25% more for your regular electricity (35p vs 28p a unit), but get four hours overnight at 7.5 p per unit - should be just right for a full charge of an i3. Certainly makes the headline economics in the first post a lot more favourable.