"does she even realize what she is doing?"

Your mom knows EXACTLY what she is doing.

She keeps repeating this behavior, because she keeps getting a payoff. (you being her slave)

She wouldn't be doing this , year after year, unless she was getting a payoff.

Now, mom has realized that the payoff is no longer guaranteed.

She is changing tactics. She is fishing. Trying new ways to "hook" you into even more guilt driven behaviour.

She thinks "hmm, my car is almost kaput. maybe i can use this to hook him into becoming my chauffeur. If he balks, i can say that it is duty , as a a good son, to always be available. I may even say that he can use the service to pay down his "debt", but keep everything vague as to how much he owes and how much this 24/7 taxi is worth.

Anything to secure the payoff.

The fact that your mom has been moody and has tried new things to hook you, leads me to believe that this is no sub-concious act.

To me, adaptation of any behaviour to achieve a similar result must be a concious act.

She is aware of what she is doing.

She must be held responsible for her actions.

Same goes for you, too.

Others have given you pointers on how to handle her on a day to day basis. Listen to them. Stop being so hyper responsive to her . Learn to deflect and delay answering her.

Just because there is a hook in the water doesn't mean you have to bite.