Exhibit 99.3

CERTIFICATION OF PERIODIC REPORT PURSUANT TO SECTION 906

OF SARBANES-OXLEY ACT OF 2002

I, the undersigned Preston A. Miller, Executive Vice President, Chief Financial Officer and Treasurer of AmeriCredit Corp. (the “Company”), do hereby certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, that:

(1) The Quarterly Report on Form 10-Q of the Company for the quarter ended March 31, 2003 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

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

Dated: May 15, 2003

/s/ Preston A. Miller

Preston A. Miller

Executive Vice President, Chief

Financial Officer and Treasurer