Filter Query question

[Eric Grobler]

Hi Solr Community

If you use a filter like:
  q=*:*
  fq=make:Volkswagen

and then the next query is:
  q=blue
  fq=make:Volkswagen

will Solr use the filter cache before the main query, or only after a "blue"
subset?
In other words will this query make more sense?
  q=(blue) AND (make:Volkswagen)

What are the do's and don'ts of Filter Queries and are there differences
between Solr versions?

Thanks
Ericz