I worked out the following on a thread somewhere:
Lease: Petrol vs EV = £200-300 more per month on EV (Let's take £200)
Fuel: Petrol £1.80 and Electric at £0.20p (A mix of 1/3rd Rapid and mostly very cheap home charging)
MPG: Petrol = 45MPG = 10MPL and Electric = 3.5M/kWh.
So 12000miles a year:
Petrol = £2160 in fuel per year.
EV = £685 in electric per year.
So 3 years fuel = £6480 and Electric = £2057.
If you can charge at home and bring your average electric cost down to 20p or less per kWh, you're onto a big win on fuel alone.
Tax = £165 and £0
So £6480+(£165*3) = £6975 - £2057 = £4918 difference over 3 years of fuel/tax.
Now add in the assumed £200 per month for 36 months and you have a cost of (36*200) £7200 extra for the EV lease.
You save £4918 on fuel, but lose £7200 on lease costs.
Net benefit on an EV = - £2282 over 3 year, 12k mile lease.
If you don't already have an EV, then you need to buy a charger etc, so it's a higher investment.
Essentially, unless you get your EV fuel cost down to almost zero, then a petrol car on a lease is cheaper at £1.80/L and 45MPG.
However it's not that simple as you have:
Fuel pricing changes (both fuels)
Fuel availability issues
Time saved/lost
Saving the planet (or not)
Miles around town vs motorway, as these change the equations.
How much time you spend on public chargers
If you have solar, that is essentially providing free electric
If servicing is really cheaper on an EV (Doesn't look it currently)
Do you already own a petrol car outright
Do you already own an EV outright
Availability of cars
Are you going into cities where ICE cars are charged an entry fee or even banned?
I think right now if you're a two car house, your best bet is one of each (ICE and EV), as you cover fluctuations and avilability.