Check with your doctor's office, or your state council on aging. I got one through the local rehabilitation center in Minnesota that deals with post-stroke, TBI and trauma patients.

The beauty was that she couldn't blame the doctor or the government. Of course, she did blame me, but I'm the oldest of 6 kids and pretty tough! As soon as the evaluation letter went to her doctor and the state DMV, we found a distant relative who "needed" to buy her car. This would not have worked if one of us or our kids bought, because she would have always seen it to and been reminded of her loss. And we could always remind her that someone who really neede it got a reliable car.