EXHIBIT 99.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Current Report of United Auto Group, Inc. (the "Company")
on Form 8-K as filed with the Securities and Exchange Commission on the date
hereof (the "Report"), I, Roger S. Penske, Chief Executive Officer of the
Company, certify, pursuant to 18 U.S.C. ss. 1350, as adopted pursuant to ss. 906
of the Sarbanes-Oxley Act of 2002, that:

         (1) The Report fully complies with the requirements of section 13(a) or
15(d) of the Securities Exchange Act of 1934; and

         (2) The information contained in the Report fairly presents, in all
material respects, the financial condition and result of operations of the
Company.

/s/ Roger S. Penske
- -----------------------
Roger S. Penske
Chief Executive Officer
August 7, 2002