What your friend is doing could be construed as a misuse. Surely a wheelchair bound disabled person needs a WAV. Unless the daughter is small and the wheelchair is a fold up that can fit in a standard boot.
The cost of the car is made up in 3 stages.
Stage 1 - Advance Payment by the customer from their own pocket
Stage 2 - For the duration of the 3 year contract, the DWP will pay the customers mobility allowance straight to Motability.
Stage 3 - At the end of the contract, the car is returned and sold on by Motability. The resale value obviously recoups the rest of the outstanding balance.
So lets say I want to order myself a new Ford Focus Titanium. It has a list price of £19,555.
Advance payment that I make is £795. That brings to cost down to £18,760.
Then I pay my allowance for 3 years. This amounts to approx £8580. This bring the outstanding balance to £10,180. Also, I would imagine that there is a further list price discount which would mean motability would have to recoup around 8k, which is the average value for a 3 yr old Focus. This is the amount that Motability have to receive on resale to achieve a 0 cost lease. Any shortfall is made up by the organisations own funds and NOT taxpayers money as many would have you believe. However in many cases Motability have actually found themselves in profit as their cars are looked on very highly by second hand buyers due to the fact that they recieve the best possible maintenance and many are very low mileage.