Sue – I’m so sorry to hear about all of your challenges. I have two adult children and I worry about them both, even though they are in good health! In spite of everything that you are facing you sound like an extremely sensible and measured person, so I’m sure that you will have no issues with getting what you genuinely deserve.
Although PIP is a dirty word for most people, there was a lot of abuse under DLA and things needed to change. However, many disabled people find the PIP process overwhelming and that’s not right. Clearly you aren’t one of them though, so if you want a new car then I wouldn’t be worrying about ordering one. How long you will wait for the car is another matter!