It’s worth remembering though that you get the GCB even if you leave the scheme when you hand the car back, so whilst it helps cash flow, you can’t say that you are only paying the figure net of the GCB. With GCB, Motability are handing you cash which you can do with as you please. Fine if you choose to use it towards the AP of the next car, but it doesn’t make the actual AP you are paying any cheaper! It will be the same with the £250. Motability give it to you in the one hand and take it back through inflated AP’s.
It just goes to show how clever the approach is though, as many people get easily fooled into thinking that they are getting money for nothing or a discount on their next car, when in reality they are overpaying to start with, only to get a small proportion of the overpayment back.