Automobile database logic
Start by thinking through a user interface.  Will the user start with the make+model+year of the vehicle?  Or will he start with "airbag"?  More maybe you want to provide both ways to start the drilldown.

Don't plan to do all the work in the database.  Plan to either have some application code to sort through the "so inconsistent" data, or throw text at the user, and let him sift through the final information.

How many different sets of info do you have?  One per make+model+year?  One per component with a service plan?

The design might be one table, with lots of columns.

Or it may need 3 tables (to start with).  One for each distinctly different vehicle; perhaps PRIMARY KEY (make, model, year).  One for service plans; this would contain an id, a TEXT field, and some meta information ('airbag', mfg's id, etc).  The third would be the "relationship" that ties the two other tables in a many-to-many relationship; it would have two ids (for JOINing to the other tables).