What's the best way to transfer someone from a wheelchair to a vehicle?

Ladl77 asked...

Does anyone have any advice on transferring someone from a wheelchair to a vehicle? I had a very difficult time with my mother during a doctor's visit this morning. I fear I will not be able to take her to her preferred providers much longer simply because I cannot lift her and she is very uncooperative (won't do what I tell her...grab here, etc.) while trying to load.