I get a motorbility car as the wife's in need of a lung transplant. Quite a good scheme really as the only outlay we actually pay for the car is for fuel, everything else is taken care of by them, tax, insurance, servicing, tyres, repairs, brakedown, ect. As for the cost to us I think she lost part of her benifit, about £48 / week.
There is a price list of what cars you can get on the net, can't remember the site tho. Not every car is available ie the sporty models as we wanted a focus ST or astra VXR but they were having none of it