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Today I clocked 10k miles in my TM3 Performance. I've done a lot more miles this year than normal by the looks of it!

Anyway, average consumption of 281Wh/mile for those 10,000miles, which is an equivalent of 144MPG in old petrol money.

With my previous TM3 Long Range, I did 37,400 miles at a lifetime average of 271Wh/mile. That one didn't have the heat pump and had the 18" aero wheels. Definitely reckon the 20" alloys on the Performance steal some efficiency, but I get a fair bit back vs the older car with the heat pump?

What is that in mi/kWh?

3.6 miles/kWh

In June I installed an electricity meter between my Henley block and the mini consumer unit which serves my EV charger.

I have been measuring kWhs consumed per the meter versus the miles per kWh shown longterm on my VW ID4. The car shoed 4.1 and the actual was 3.6 for 2,500 miles in August and September. Quite a difference. Mi per kWh are decreasing now that the weather is cooler and wetter.

Anyone else done a similar comparison?

John_S wrote: ↑Tue Oct 31, 2023 5:11 pm In June I installed an electricity meter between my Henley block and the mini consumer unit which serves my EV charger.

I have been measuring kWhs consumed per the meter versus the miles per kWh shown longterm on my VW ID4. The car shoed 4.1 and the actual was 3.6 for 2,500 miles in August and September. Quite a difference. Mi per kWh are decreasing now that the weather is cooler and wetter.

Anyone else done a similar comparison?

I presume your electricity meter measures the amount of energy used during charging whereas the car presumably measures how much is used from the batteries - is that correct? If so that suggests an 88% efficiency does that sound reasonable?

John_S wrote: ↑Tue Oct 31, 2023 5:11 pm In June I installed an electricity meter between my Henley block and the mini consumer unit which serves my EV charger.

I have been measuring kWhs consumed per the meter versus the miles per kWh shown longterm on my VW ID4. The car shoed 4.1 and the actual was 3.6 for 2,500 miles in August and September. Quite a difference. Mi per kWh are decreasing now that the weather is cooler and wetter.

Anyone else done a similar comparison?

It is standard for there to be a difference because the car measures miles per kWh being discharged from your battery and your meter is measuring power going into the charger. There are significant charging losses...

I thought as much, but just wanted to make others aware of the possible extent of the difference and the knock on effect on pence per mile and equivalent mpg etc.

Bjorn Nyland has done some good videos on the charging losses with EVs and how they are different between cars, but also between AC and DC charging.

It's true that we're not getting 100% of the picture in terms of energy/mile from the car displays, but we can be sure it's still orders of magnitude better than the efficiency (or lack thereof) of fossil burning ICE vehicles.

I think around 10% losses for charging is an acceptable figure. This chart, suggests similar:




Just to say, that some of these charts vary, as many will include an additional 10%-20% to reflect re-gen*, when comparing overall efficiency v's a petrol/diesel car, so you may see 85%+ for a BEV, and 30%(ish) for a HFCV.

*To reflect more average driving, including braking and stop start driving - rather than just a simple comparison.