I'd like to build a contact database of fleet operators (>= 5 vehicles) in Texas.

Of course, the better result would contain more information.  Minimum
information should include organization, contact name, address, and
telephone.  Nice extra data could include email, website, number of
vehicles, age of fleet, fleet-specific data (e.g., management
practices) and so forth.

I've spent enough time and exhausted enough search strategies to
include a nice tip if the data can be located.