Jan,
First of all, I am so sorry to hear about your dh's health.
Not sure about the vehicles. But to share our experience----my mil's cancer took a turn for the worse in 4/04. She was put on hospice and we took care of her in our home for 4 months. My dh got power-of-attorney (all he needed was a document he printed off the computer and a notary, then he filed the document with the local court). But financial questions/issues started to creep up when we were having trouble paying all her bills (and our own) when we needed to take the Family Medical Leave Act from our jobs to care for her. We had decided to sell her home in order to alleviate many of her bills. The best thing we did was to hire an estate lawyer. She really took time and spelled everything out for us and told us exactly what we needed (or could) do financially/legally.
We perhaps needed an estate lawyer more than you because we had family members (my dh's 3 brothers) who were seeking financial gains from my mil's estate and were willing to sue my dh to get what they wanted. The estate lawyer totally protected us in regards to financial decisions that were made. It left no room for dispute.
Also, Ethansmom mentioned a health care POA. We did this early on and it was invaluable. It allowed us to discuss specifics with my mil's oncologists/doctors, pick up medical files, prescription drugs etc. The HIPPA laws can be very strict. On a side note, I cannot say enough about the hospice system either. We had nurses, nurses aides, clergy, social workers & volunteers etc at our beckon call. They helped the whole family deal with the process of losing a loved one. The social workers were able to help us with some financial concerns as well. Hospice was 100% paid by my mil's Medicare.
I wish you luck with the vehicle situation. I sincerely hope the car company can work something out with you.
My prayers are going out to you and your family during this difficult time. Hang in there Jan.