[Paul]

It's quite complex. Smarter folk than me may pop in and add to the help/advice but you have many factors at play. Cost per kWh of the electricity and the miles/km per kWh at any given time and/or on average (real world) then the cost cost per litre or gallon of fuel and the current or average miles/km per litre/gallon (real world) of an ICE vehicle. Do you then also factor in other service costs broken down by the mile, don't know. Where you would get these figures would be another challenge.

All possible, I think Nissan have produced an iOS app which tries to tell you what you'd be saving by having an EV, can't recall it's name though, sounds similar to what you're looking to achieve.

 

[Paul]

I think cost of a car is different to efficiency/cost per mile.

However if you go down that route, what really matters is residuals, say over three years. Not purchase price, but depreciation. This probably isn't a great thing in terms of EVs (at the moment), but it's fairer than saying, for example, a MINI is more expensive per mile than a Fiesta because it costs more like-for-like size and feature wise.

It's also really complex and model specific, so maybe WAY beyond the scope of an app.

 

[Paul]

Miles per kWh vary considerably with the weather, driving technique, road conditions, and terrain. Some days I see 2 mi/kWh... other days I can easily see 5... both without varying my driving technique or road conditions much... (mostly a weather change).

As does MPG, so despite all that it's a fairly reasonable way to compare.