Ok, for a bit more detail for the OP.
We sold a 08 Vauxhall Corsa - If we sold it private - we'd have got about £3,000, maybe £3,250?
We got £2,600 for it from webuyanycar after they quoted up £2,900.
The car itself was in okay condition - apart from when the Air conditioning was on, it made a really weird noise when pulling off in 1st gear. And the engine light was on because of it.
We called them, booked an appointment the next day at a time of our convenience, and I took it in.
They have a little tick sheet which when they look at the car body (a pretty detailed inspection to be honest) they look for little scratches or bumps (individually listed).
The guy told me that our car had less than 5 of each - which is the first bracket (1-5), so it was listed as very good condition.
They then turn the engine on, floor the pedal to make sure there's no black smoke coming out the back and then look inside the car.
They look in the boot for your wheel etc.
They then drive it back and forward on their car park, and check the gears go into gear nicely.
So, we had a couple of bumps and a couple of scratches - all general wear and tear - and I they knocked off £300 for them, which I thought was fine.
You can pay £40 to have the money in your bank by the next day, or you can wait for 5 working days and it'll be there.
Fill in a couple of forms, give them your cars V14 (I think), sign a couple of items and bob's your uncle - car sold.
Took about 1 hour from start to finish - The guys were nice, professional and respectful.
I thought they gave a solid service. Yeah, I suppose the extra £400 would have been nice, but I've sold a car privately before and had problems with time wasters and people that want to test drive it and arse around for an hour - so i suppose the speed of service was definitely worth that difference.
Hope that helps