I’m not quite sure whether i should be impressed or kind of shocked that you still peddle this nonsense.
One last time:
Take your car. Put exactly one gallon of petrol in it. Drive until the engine sputters out, measure the distance. 50 miles, great. Your car does 50 miles per gallon. Refuel the car with a single gallon of fuel, attach a battery with 20kwh for 50 miles range and an electric motor. Your car now does 100 miles. That makes 100mpg. That’s what the car is telling you, and it absolutely is the correct number to show. Because MPG only refers to petrol/diesel used. But here’s the twist: the car now also tells you that you not only used 1 gallon of fuel for 100 miles, it also tells you that you used 20kwh for 100 miles. Giving you the numbers 100mpg and 2.5 m/kwh.
These numbers are indisputably correct. There’s no argument to be had here. The argument you’re trying to force is that these numbers lie and the real cost per mile is higher than it suggests, but it doesn’t suggest a cost per mile at all. It just objectively tells you how much energy, and what energy mix you used for a given distance. That’s their only purpose.
That’s why i think you’re deliberately obtuse. This example up there? That goes for pure ICE cars, too. If i refuel one gallon in my X1, just drive it until it sputters out, i get 42 miles in distance. Now i refuel one gallon, but have my wife tow me 300 miles while idling. What’s the car going to tell me?
To suggest that a car should take your local petrol and electricity prices into account when showing you your average efficiency (effectively turning it into a “cost per mile” gauge) is just asinine. The only surprising thing (or not) is that you don’t peddle this nonsense for ICE cars, where the MPG is just as inaccurate, since again, it only tells you how many units of petrol you burned for a given distance. And of course, in your example, i’d also get better MPG because petrol here is cheaper than where you live.
Here’s a fun one. Explain how it should be done, other than giving you “units of petrol used over X distance” and “units of electricity used over X distance”, since that’s what the car is telling you right now. What would be a system that improves that?
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.