Great news richard happy for you, well worth the drive twice for the offer. Is nice when you can take advantage of the new Quarter coming often most cannot and you got to wait till you see the price for the Quarter you can actually order In.
I ordered my honda back in jan and picked it up last monday and it had risen £600 since i had a test drive and was able to order the car and could only get £200 off and a free tank of fuel but very happy still, is what it is..
As for the main question it varies but the dealers do not set the ap any reduction they pay to MB on your behalf who are buying the car outright for us to lease. so it really depends on the 3 year projected value and for many reason i only see values of most ice cars decreasing in residual value as we get pushed more towards zero emissions. The Low emmision offerings are poor imo so it is where we are and covid has not helped and the green solution to the future has brought forward the agenda qucker than alot thought.
also technology more of it cost more so prices go up. like the cost of smart phones now compared to before for example all has an effect on the ap. Mein while the allowance only goes up less than the real rate of inflation and this also is causing an effect plus the cap MB set.
Goodnews though you get £600 gcb instead of the £250 i got 3 years ago. So in richards case thats £1100 towards the AP. In my case £800 plus a full tank of juice.. but we are getting less and less high end cars and trim levels on the scheme or higher AP with for me makes some cars just not viable.