Hi Matthew. Yes it’s possible and I’ve done it. The dealer has to agree to it though and accept some risk. As you probably know, an order is only placed when a dealer secures a manufacturer build slot. The Motability part is just admin. The two rarely happen simultaneously anyway. We ordered our current car (VW Tiguan) in January 2018, which was 5 months before our previous lease expired and two months before our official 3 month order window. This was due to there being 5 month lead times on the Tiguan at the time. When March came, the dealer did the Motability admin, placing the order on their system, but we were already two months into the actual order. The car arrived in June, which was when our previous cars lease expired (in fact we had to wait a week or so for the exact date to occur), so no need to extend the old lease and we got the new car bang on the lease end date.
I should say that January (when we ordered) and March are both within the same Motability pricing quarter. There would be a big risk if you ordered before the quarter that your official 3 month order window is in. The AP may have gone up (in which case you have to pay it, but if it has gone down you will pay the lower AP) but worst case scenario is that the car is removed from the scheme, in which case you can’t go ahead with the order and would have to cancel, hence the risk for the dealer, although they could most likely transfer the order to another customer (and change spec etc) if the car hasn’t been built.