So just to follow up, Over 7 weeks after I sold it to Cazoo, they finally listed it for sale. £53650 (I sold it for £49450). So around 8.5% markup. The pictures show they've repaired the minor kerb damage to the front two wheels, and also they replaced the passenger mirror housing that had a scratch on it. It was parked for quite a while at a company that has repair contracts for major leasing companies. Allowing £300 for the work, that's just under 8% mark-up. They actually listed it last night for £2K less, so someone musta decided it was on there too cheap. I'm surprised that they omitted listing some of the major extras.
Anyhow, Cazoo is offering £44575 if you want to sell the car to them, WBAC is offering £43400. WBAC was previously around £2K or so less than Cazoo. Even allowing for the fact that the cazoo computer might realise it has a "very similar" car on its books, it looks like the offer prices (at least for this make/model) have softened £4-5K since I sold it.
Whilst I await for the KIA EV6, I have the use of a 2020 petrol sportage with 5K on the clock, no downpayment, no contract, just calling up each month to pay them £320, or otherwise leave the car. £320 was more than I had originally considered, but at the time I was thinking about something several years old. whereas this is a pretty fresh car. V5c and tax in my name. I guess the £320 a month insulates them from the monthly depreciating value of the car with a bit of profit. Found an online insurance quote for a good price that only referenced having to be the registered keeper (not the owner) as an assumption, so happy to go with that.
So far, things have worked out roughly as envisaged.