To cite the car package in publications use:

  Fox J, Weisberg S (2019). _An R Companion to Applied Regression_,
  Third edition. Sage, Thousand Oaks CA.
  <https://www.john-fox.ca/Companion/>.

A BibTeX entry for LaTeX users is

  @Book{,
    title = {An {R} Companion to Applied Regression},
    edition = {Third},
    author = {John Fox and Sanford Weisberg},
    year = {2019},
    publisher = {Sage},
    address = {Thousand Oaks {CA}},
    url = {https://www.john-fox.ca/Companion/},
  }