Fuel cost for running my SR+

[mo.dilwar]

I’ve had my M3 since 9th November and only just ticked over the 1,000 mark on the odometer (not many miles I know, but living in and around London, I drive around 5-6k miles a year).

Looking at the Lifetime trip computer readings, it says I’ve done an average 304 Wh/mi and consumed 307 kWh after exactly 1,010 miles.

If I did this all with home charging it would’ve cost me 13p per kWh on my electricity traffic with Bulb energy, making it a total of £39.91. But I actually filled up 196 of those 307 kWh at SuperChargers for free. So actual total fuel cost so far is 111 kWh x 13p = £14.43.

Sure the Tesla SC free charging won’t last for ever (I only have 204 kWh left from my referral bonus). But comparing my home charging cost with the best case scenario on an ICE executive saloon - doing similar mix of local road, dual carriageway and motorway miles - I would get 400 miles max per full tank. Each tank of fuel costing say £60 @ £1.25 per litre.

So 2.5 tanks of fuel to do 1,000 miles. Total petrol cost £150 vs sub £40 for home charging. £110 saving per 1,000 miles is pretty great I think. Plus this was during the cold winter, my efficiency should improve quite a bit in the spring and summer.

 

[Jason71]

The 307 is the kwh consumed driving you will have consumed more than that. Home charging will have a 10% loss on a 32amp more (15% maybe) on a umc. Also not sure that will include energy used while not driving like vampire drain, sentry mode and preheating etc.

 

[mo.dilwar]

The 307 is the kwh consumed driving you will have consumed more than that. Home charging will have a 10% loss on a 32amp more (15% maybe) on a umc. Also not sure that will include energy used while not driving like vampire drain, sentry mode and preheating etc.

Valid points for sure. But even taking them into account, I can’t see the real consumption being any more than 350 kWh max. So £45 in home charging.

Also I think I’m being quite generous about the ICE efficiency in my comparison.

 

[Adopado]

Valid points for sure. But even taking them into account, I can’t see the real consumption being any more than 350 kWh max. So £45 in home charging.

Also I think I’m being quite generous about the ICE efficiency in my comparison.

... or 350 kWh for £17.50 on Octopus Go tariff ... go on ... there are people, ahem, who would offer a referral code! See sig below:

 

[mo.dilwar]

... or 350 kWh for £17.50 on Octopus Go tariff ... go on ... there are people, ahem, who would offer a referral code! See sig below:

Yes it’s something I’m thinking about. Need to assess my entire home electricity usage to work out if it’s worth while at this stage. On average our usage is 250 kWh to power the home and 100 kWh to charge the M3.

Also a bit put off by stories of long delays in getting the Octopus smart meter installed which would potentially negate any cost savings, and the fact I’ll likely need to upgrade my home charger with smart features that would allow for better charge scheduling.

 

[webbah]

Don’t forget the savings from ICE annual maintenance. Oil changes, etc. I switched from an Audi RS4 to Tesla and over a 3 year period I calculated that I save close to 30K Swiss Francs with fuel, insurance, annual road tax and maintenance savings. Switzerland is expensive though.

 

[Jason71]

Valid points for sure. But even taking them into account, I can’t see the real consumption being any more than 350 kWh max. So £45 in home charging.

Also I think I’m being quite generous about the ICE efficiency in my comparison.

Well you say that but prompted by your thread I decided to look up my real efficiency.
My M3 LR has covered 3221 miles since November at, according to the display 301Wh/mi a total of 970 kwh.
However
I have done all of my charging at 2 7KW chargers both of which record the Energy consumed. Since this is done using simple AC metering I have no reason to doubt that it is accurate. Across the 2 chargers I have consumed 1264kwh. So that is an additional 294kwh. or 30%.
So this would give me 392wh/mi. In reality the best use of wh/mi is in figuring out how long your battery will last on a trip so the 301wh/mi is a more useful figure but if wanting to know the true cost then it looks like for me it is actually +30%.
Obviously this will be different for everyone. Based on things like how you charge, amount of preheating and sentry mode ( about 20 hours per week for me FYI) but your suggestion that it wont me more than +15% sounds a bit conservative to me.

 

[KennethS]

Obviously this will be different for everyone. Based on things like how you charge, amount of preheating and sentry mode ( about 20 hours per week for me FYI) but your suggestion that it wont me more than +15% sounds a bit conservative to me.

I would surmise that preheating while on charge, use of sentry, and the sleep/wake cycle of the vehicle (and how often it is woken by checking status via the app) would have the biggest effect. I have SMETS2 metering and when the car is charging at 7.2 KW the readings on the usage meter is pretty consistent with what I would expect to see (adding the normal house draw to the 7.2KW). I have the TWC but would think brand of wall charger makes small differences if any. My car lives in a pretty well insulated garage and preheating definitely consumes quite a bit of power.

 

[rotor2k]

the fact I’ll likely need to upgrade my home charger with smart features that would allow for better charge scheduling.

There are quite a few issues with smart home chargers, you're much better off with a dumb one.

 

[rEV gadget]

Also a bit put off by stories of long delays in getting the Octopus smart meter installed which would potentially negate any cost savings, and the fact I’ll likely need to upgrade my home charger with smart features that would allow for better charge scheduling.

I’m currently with Octopus and been waiting for a SMETS2 meter since September 2019. I applied to change to their Agile tariff on the 5th Jan and had my meter installed on the 13th. Presumably they prioritise those wanting to go on the smart tariffs?

 

[mo.dilwar]

Well you say that but prompted by your thread I decided to look up my real efficiency.
My M3 LR has covered 3221 miles since November at, according to the display 301Wh/mi a total of 970 kwh.
However
I have done all of my charging at 2 7KW chargers both of which record the Energy consumed. Since this is done using simple AC metering I have no reason to doubt that it is accurate. Across the 2 chargers I have consumed 1264kwh. So that is an additional 294kwh. or 30%.
So this would give me 392wh/mi. In reality the best use of wh/mi is in figuring out how long your battery will last on a trip so the 301wh/mi is a more useful figure but if wanting to know the true cost then it looks like for me it is actually +30%.
Obviously this will be different for everyone. Based on things like how you charge, amount of preheating and sentry mode ( about 20 hours per week for me FYI) but your suggestion that it wont me more than +15% sounds a bit conservative to me.

The energy use/cost for sentry mode and preheating is probably irrelevant for my comparison as I don’t know of any ICE vehicles that have these features, and the use of these features on a Tesla are purely the owners choice.