Based on prior knowledge, the number of doors can be a relevant feature when determining the decision to buy a car. Here is the analysis and corresponding dictionary:

Analysis:
- Unacceptable: It is likely that cars with 2 doors would be classified as unacceptable due to limited space and practicality for everyday use. However, it is also possible that cars with more than 5 doors could be classified as unacceptable if they are of poor quality or have other negative features. 
- Acceptable: Cars with 3 or 4 doors are commonly considered acceptable since they provide a good balance between space and practicality. Cars with 5 or more doors could also be acceptable, depending on other features and specifications. 
- Good: Cars with 3 or 4 doors are commonly seen as good choices due to their balance between space and practicality. Cars with more than 5 doors could also be classified as good depending on other features and specifications.
- Very Good: Cars with 4 or more doors are commonly considered very good choices as they offer ample space and practicality for passengers and cargo.

Dictionary:
```json
{
	"unacceptable": ["2"],
	"acceptable": ["3", "4", "5more"],
	"good": ["3", "4", "5more"],
	"very good": ["4", "5more"]
}
```