Using the Search Filter with Entry Fields
{% set range = entry.model %}
{% set categories = craft.categories.slug('not preferential') %}
{% set entries = craft.entries.section('offers').search('title:' ~ range).relatedTo(categories) %}


If you are only searching titles I would add that in the search params as it will help the effectiveness of the search. In addition when setting a variable you do not need to use the {{}} syntax as it will automatically use the string representation of the the field if it is a text field.