We need two sinultaneous things to have a working system: where do we put things depends on what routines we set ourselves to check those lists. The objective is to see things at the right time in the right place.
The right place may be the context and the right time is when we look at that context list.
I guess ‘take the car to the shop’ is not a single task, and that’s why I don’ t know where to put it.
Before I can take the car to the shop I have to find someone who will pick me up in he shop and take me to work, then I have to schedule the visit, and so on
So if input the whole thing in the ‘car’ context it doesn’t help because I cannot just drive there and leave the car without those prior arrangements.
Tasks should be small and simple enough so that in each context I can just do them without any external dependency other than my own time and energy.