If you order extras or overly expensive paint colours the dealer puts them on what’s called a supplementary invoice. That’s always payable by the customer, and can be subject to additional contractual terms set by the dealership.
Or to put it another way, the dealer can, if stated before the application is made, charge the customer for the extras added but that are not covered by Motability in circumstances where the application is cancelled.
I’ve only ever dealt with 2 cases of a dealer insisting on that.
On that point some manufacturers (notability MINI) have now stopped allowing any extras being added to the factory build. The MINI you pick must match the product code that MINI has agreed with Motability. That started in Q4 2025
Motability’s terms with the Dealers / Manufactures clearly state that the actual sale only happens at the point of entering the PIN (aka electronically signing the lease agreement). At that point 2 things happen. Motability purchases the car (so before that the car has cost them nothing*) and Motability leases the car to the customer.
From professional conversations with Motability they are more than happy for customers to walk/wheel away at the last second. The car has to be right for the customer, as it costs Motability a lot lot more once the PIN is entered, and costs them nothing* before.
Should a customer be able to cancel a car that’s not right for them when there is no legal agreement in place – yes.
Should a customer then be able to reorder the exact same car at a lower AP …. that’s an interesting question that I don’t really have an answer for. I personally think that it should be like Amazon’s preorder guarantee; you should pay the lowest AP between placing an application and handover
*Technically it costs Motability to send out some paperwork to the customer, the pack that contains the PIN and the terms conditions book – but that’s a legal requirement as it contains contract information.