Yeah, it's my petrol car (a 2Litre Altezza) calculating how much money I have actually saved. 

You'd probably think my Mrs 1.6L Kia Rio would be Comparable to the Leaf on paper, but once you drive both, the Leaf is more car than the Kia. Incidentally the Altezza isn't actually any bigger (or heavier) than a Leaf - those Leaf's are bigger than they look.

Yeah, as said earlier in the thread, the higher the Km's you are doing, the faster the pay back.

If you use the same capital cost logic to analyse swapping a petrol car for a petrol car, nobody would ever replace their car because you would take decades to see payback (if ever), but people (needlessly) do buy replacement petrol cars out of desire/image/envy/fashion/nostalgia etc.

But for sensible and modest people who don't have disposable income to throw around, the optimum time to upgrade to EV is when your old ICE dies - no argument. You're buying another car anyway so the capital cost between EV and ICE is much less of a question, and a slightly more expensive EV is easy to justify when you consider that in your analysis above, you're saving $2K a year in fuel (plus the servicing savings, registration savings etc).

Off topic, but buying any car on your mortgage without increasing your principle payments is more expensive than buying same car on a credit card. Think about it - you don't actually start paying the car off for another 25 - 30 years. Allowing people to put other things on mortgages without increasing payments is a system to keep customers indebted for life.