In the Motability scheme you exchange part or all of your mobility allowance to lease a car of your choice. These cars are available at a fixed weekly amount for the whole of your lease agreement. The remainder of your allowance, including any annual increases, will be paid directly to you by the Department for Work and Pensions (DWP) or Veterans UK allowance you receive.
To have a wider choice and select from the most expensive and advanced available vehicles you can also pay a one-off upfront advance payment. This is needed because your mobility allowance may not cover the cost for some larger or more expensive cars. These cars are allocated with an Advance Payment which represents the difference between the amount your mobility allowance covers over the three-year agreement period and the overall cost of the car you choose.