Restricted (or no) mobility, virtually unable to walk or to make walking progress due to severe mental impairment. You may have to appeal and go to tribunal even with a clear diagnosis and countless supportive letters from medical professionals.
If you are successful you will be awarded the mobility component (higher rate) of disability living allowance. This is about £51 per week and you can either use this for taxis, fuel, towards a car from elsewhere, or choose to lease a car through the scheme. The type of car you have will depend on how much you have to put down as a deposit.
Sadly, some families, those needing one to accommodate a wheelchair or two, don't have £10k needed to lease the type of vehicle that they need.
In my case, it took a year for the award to come through so the backdated money went towards the deposit. My son's car only needs to be able to fit his wheelchair buggy into it so luckier than most who qualify.
Pros are that the motability vehicle is taxed and insured and you will also have automatic entitlement to a blue badge. Cons, well, as I mentioned. In many cases families have to decide if they need the money or the car more.
I think that's the bare bones of it and I'm happy to be put straight on anything. But it most certainly isn't a case of filling in a form online as the DM is suggesting today 