There are many things that need to be worked out in detail.
VAT. If Motability can get a “special case” (which is a bit suspect in itself as you should not have rules modified for 1 business or charity) then the the UK could make a wider allowance for UK car brands.
Alternatively, with the cost savings on administration and discounts required by Motability there would be more savings to absorb the VAT element
Or just add the VAT element to the residual value at the end of the lease. Afterall many Motability cars at the end of 3 years have very low mileage and look almost new and very desirable on the used market
Credit Scoring & Eligibility Similar to what happens now, the mobility payment could be sent direct to a leasing company or if someone wants to pay more, from their personal account. There could be more flexibility in monthly payments (higher for a better specked car) or lower monthly for a longer lease.
If customers stop paying the lease or become intelligible then much like now, sadly the car gets returned.
Leverage Affinity Many car owners have an affinity to one particular brand and will always select cars with the same badge. If you have built a relationship with a dealer and have looked after your cars then the dealer is more likely to work with you to pre-order a vehicle knowing that they will get a great preowned car in 6 months time.
Reading a lot of the posts on the forum, there is a lot of frustration with Motability and the service which now offers little in the way of service to customers or dealers and that if a core group of brands (Ford, Nissan, Peugeot/Citroen etc.) got together they could formulate a replacement scheme between them.