Help me understand company car schemes

[OttoMattik]

I've only ever bought or privately leased cars in the past. One of the perks I get with my job is a company car allowance using Zenith.

Salient details:

• 40% tax bracket
• I get a £5500 car allowance, or the option to take £5000 as a cash sum (which I do).
• Equates to £416ish a month, which after tax would be £250.
• The current PCH car I have costs me £235 a month, so that does cover the cost of leasing nicely but I am responsible for my own insurance, servicing, tyres etc. Car is a BMW 2 Series Gran Tourer.
• In terms of running costs (these are all approximations but not too far off the mark)
• Insurance - £40 a month
• Fuel - £150 a month
• Servicing - £12.50 a month (£300 service required before the car goes back in 2 years)
• Tyres - £5 a month (say £120 to replace worn out tyres before lease ends though may get away with nothing as I'd hardly do 10k miles in them).
• Total run costs (after tax) - £457.50

There's a couple of things that are pushing me towards the company car scheme:

• £1500 cashback if I order a car before Christmas - in a push to go greener/all electric.
• The range of cars on offer through Zenith are better than what I get with personal leasing.
• I can get a Tesla Model 3 Standard one for £447.97 (which includes the BIK, its £741.71 gross but the NI and TAX savings at 40% bring that down considerably).
• Add on charging costs of say £30 a month
• Total - £477.97

Costwise - we're roughly at par with either option but the pro with the company car scheme is that I get to drive a more expensive car - Tesla or a Polestar 2 (latter would be even cheaper). Plus I'm not really tied in for the whole duration if I leave my job for another, as I can hand it back for a small admin fee (£250ish).

Have I understood this correctly? What would you do in this scenario?