Grouping of vocabularies
Assuming D7, you can add a field to the vocabulary entity to group the vocabularies together.

For example, you could add another vocabulary "Group" that contains your vocabulary group terms. You could then add it either as a select or free-tagging style term reference field on your other vocabularies and link them that way.

Admin > Structure > Taxonomy > Edit Vocabulary > Manage Fields

You may also want to consider using a single hierarchical vocabulary where the terms are nested under a parent term, e.g 'Vehicle' (recommended)