In N Out

In and out the car. For any of the reason that you cannot easily in and out the car. Make sure exercise daily not just walking, but some other exercise to enhance muscle both arms and legs. Why arms because you are going to need a lot of help from your arms. If you only want other people to help you get in and out of the car. Then you probably need to stay home and never get out of the house. Or you can consider moving into a nursing home. There will be people to help you 24/7 for anything.
For getting into the car you may need to use your hands to help your legs to get in the car. Get out of the car is more complicated. First step, of course opens the car door. From second step you are going to use your arms a lot turn your body 90 degrees to your right or left depends on which side that you sitting on. Third now your legs are out the car with one arm holding on the body of the car the arm holding on the car door slowly move your butt toward the edge the seat. Lastly, with the help of your both arms slowly standing up. Here you may use the walker to help to steady your step or someone can be there to make sure your safety.
Never assume that because you are old so people has to help you with everything. If you don't want to help yourself, then nobody can. Remember the rule of use if or lose it.
Again, I have to say safety first. If you are not capable or strong enough to help others. Don't  do it otherwise there will be two injuries instead of one. And don't let abusers waste your empathy.
P.S. For the people who lend the helping hands. When you are trying to help someone up, please do use the whole arms not just the hands and always stay lower for better balance to prevent injury or accident. For the people that need to be helped. Don't be afraid to hold on the body of the car or the wall to make sure your own safety you rather dirty your hands than fall down.