I'm guessing you get 20k+ miles out of them
I've surprised myself that I got nearly 40,000 miles out of mine. Yes some Hooning about, but 90% of my mileage is motorway cruising ...
I think they were £400 each to replace, so 400 x 4 / 40000 = 4p per mile - not exactly "nothing" (10,000 miles p.a. = £400 on tyres)
taxed at no more than 26%
Company has paid more corporation tax (because it didn't have the write-off of the vehicle). Relevant for an owner-manager presumably ...
(Sorry if you already factored that in, this isn't my subject!)
No BIK as buying personally
unless you are doing mega business miles?
Even if you are doing mega business miles: as a self-owned car you could charge business miles to the company at normal AA rates In terms of Fuel (assuming tyres and insurance would be same-as whatever else you might drive):
30 MPG Petrol @ 1.20 / L = 18p / mile
333 wH/mile (3 miles per kWh) @ £0.08 per kWh (e.g. E7) then 2.7p/mile cost to you
If you can charge at work then company can pay for that as a perk, with no BIK. Assuming you charge at work 5 days a week, and you drive same distance at weekends as weekday commute, that's 5/7ths paid for at work so your per mile cost is now 0.8p/mile ... although it might actually pan out that you charge at work for all your company mileage, which is during the week, and your weekend mileage is "almost nothing" and if you visit Rellies you'd be stopping, for free, at a Supercharger anyway ... or using their 13AMP plug when you get there ...
I've heard 90 battery's & range are 25% worse than 100's?
These are figures taken from ABPR for a "warm day", which i think are good enough for real-world range assumption:
MS75D 324 Wh/mile, Range 203 (best to deduct e.g. 20 miles "buffer")
MS100D 324 Wh/mile, Range 274
MS P100D 340 Wh/mile, Range 260
For my MS P90D ABRP gives 340 Wh/mile, Range 217, (I think my actual real world range is 220 miles)
So I would say a P90 is 15% less range than a P100, and not 25% less. That's with "small wheels", the bigger wheels will eat range (maybe as much as 20%, in either car)
Unless you can actually avoid a recharging stop, on a journey, in a 100 then its not worth worrying about. In terms of extra charging time its "tiny". That's on the basis that you already had to turn off the motorway, at the same location, to charge in a 100 anyway - it takes 5 minutes to get off the road, and back on again. You need to aim to charge within the optimum range which is 10% to 70%, and that's if you are on a long trip. In UK its more likely you are only charging "part of that" so you have enough to reach destination, not enough to "fill the tank".
10% to 70% is the same charging time in all models; the P90 will gain 132 miles, the P100 will gain 156 miles
On any journey above 200 (allowing 20 miles for "spare") the P90 has to charge, and up to 240 miles the P100 does not need to charge
If your journey is, say, 300 miles and you Supercharge at 200 miles, and you want to arrive with 20 miles spare
The P90 is at 10% and has 20 left, and needs to gain 100 miles = add 45% = 22.5 minutes
The P100 is at 26% and has 60 left and needs to gain 60 miles (40 for journey, 20 for "spare") = add 23% = 11.5 minutes
So on a 300 mile journey you save 10 minutes. Proportionately less for any journey between 240 and 300 miles.
Driving across France the savings are more significant