SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported)

November 3, 2015

AmeriCredit Automobile Receivables Trust 2015-4

(Exact name of registrant as specified in its charter)

AFS SenSub Corp.

(Exact name of depositor as specified in its charter)

AmeriCredit Financial Services, Inc.

(Exact name of sponsor as specified in its charter)

Registrant’s telephone number including area code - (817) 302-7000

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

AFS SenSub Corp. (“AFS SenSub”), as depositor, and AmeriCredit Financial Services, Inc. (“AmeriCredit”), as sponsor, will cause a newly formed issuing entity, AmeriCredit Automobile Receivables Trust 2015-4 (the “Issuing Entity”), to issue $175,000,000 Class A-1 0.50000% Asset Backed Notes (the “Class A-1 Notes”), $100,000,000 Class A-2-A 1.26% Asset Backed Notes (the “Class A-2-A Notes”), $235,000,000 Class A-2-B Floating Rate Asset Backed Notes (the “Class A-2-B Notes” and together with the Class A-2-A Notes, the “Class A-2 Notes”), $202,170,000 Class A-3 1.70% Asset Backed Notes (the “Class A-3 Notes”), $76,720,000 Class B 2.11% Asset Backed Notes (the “Class B Notes”), $95,240,000 Class C 2.88% Asset Backed Notes (the “Class C Notes”), $93,651,000 Class D 3.72% Asset Backed Notes (the “Class D Notes” and together with the Class A-1 Notes, the Class A-2 Notes, the Class A-3 Notes, the Class B Notes and the Class C Notes, the “Publicly Offered Notes”), $22,219,000 Class E 4.31% Asset Backed Notes (the “Class E Notes”), and an Asset Backed Certificate (the “Certificate”), on November 12, 2015 (the “Closing Date”). The Publicly Offered Notes will be registered under the Registration Statement. This Current Report on Form 8-K is being filed to satisfy an undertaking to file copies of certain agreements to be executed in connection with the issuance of the Publicly Offered Notes, the forms of which were filed as Exhibits to the Registration Statement.

The Publicly Offered Notes evidence indebtedness of the Issuing Entity, the assets of which consist primarily of “sub-prime” automobile loan contracts (the “Receivables”) secured by new and used automobiles, light duty trucks and vans. The Publicly Offered Notes will be sold to Credit Suisse Securities (USA) LLC (“Credit Suisse”), Goldman, Sachs & Co. (“Goldman Sachs”), J.P. Morgan Securities LLC (“J.P. Morgan”) and Wells Fargo Securities, LLC (“Wells Fargo Securities” and collectively with Credit Suisse, Goldman Sachs and J.P. Morgan, the “Representatives”), Barclays Capital Inc. (“Barclays”), BNP Paribas Securities Corp. (“BNP Paribas”), Deutsche Bank Securities Inc. (“Deutsche Bank”) and RBS Securities Inc. (“RBS” and collectively with the Representatives, Barclays, BNP Paribas and Deutsche Bank, the “Underwriters”), pursuant to the Underwriting Agreement attached hereto as Exhibit 1.1, dated as of November 3, 2015 (the “Underwriting Agreement”), among AmeriCredit, AFS SenSub and the Representatives.

The Issuing Entity was formed, and the Certificate will be issued, pursuant to the Trust Agreement, attached hereto as Exhibit 4.2, dated as of September 24, 2015, as amended and restated as of November 4, 2015 (the “Trust Agreement”), between AFS SenSub and Wilmington Trust Company (“WTC”), as Owner Trustee. The Publicly Offered Notes will be issued pursuant to the Indenture, attached hereto as Exhibit 4.1, dated as of November 4, 2015 (the “Indenture”), between the Issuing Entity and The Bank of New York Mellon (“BNYM”), as Trustee and Trust Collateral Agent.

AFS SenSub will purchase the Receivables from AmeriCredit pursuant to the Purchase Agreement, attached hereto as Exhibit 10.1, dated as of November 4, 2015 (the “Purchase Agreement”), between AmeriCredit and AFS SenSub. The Issuing Entity will purchase the Receivables from AFS SenSub pursuant to the Sale and Servicing Agreement, attached hereto as Exhibit 4.3, dated as of November 4, 2015 (the “Sale and Servicing Agreement”), among the Issuing Entity, AFS SenSub, AmeriCredit and BNYM, as Trust Collateral Agent.

2

AmeriCredit, as Servicer, will agree to perform servicing duties with regard to the Receivables pursuant to the Sale and Servicing Agreement and will also agree to serve as custodian of the Receivables pursuant to the Sale and Servicing Agreement. JPMorgan Chase Bank, N.A. (“JPMorgan Chase”) will agree to provide its banking services for the deposit of remittances related to the Receivables pursuant to the Lockbox Account Agreement, attached hereto as Exhibit 10.2, dated as of November 4, 2015 (the “Lockbox Account Agreement”), among BNYM, as Trustee, AmeriCredit and JPMorgan Chase, as Processor, and Regulus Group II LLC (“Regulus”) will agree to collect and deposit remittances related to the Receivables into the lockbox account pursuant to the Lockbox Processing Agreement, attached hereto as Exhibit 10.3, dated as of November 4, 2015 (the “Lockbox Processing Agreement”), among BNYM, as Trustee, AmeriCredit and Regulus.

1.1 Underwriting Agreement, dated as of November 3, 2015, among AmeriCredit, as Sponsor, AFS SenSub, as Seller, and the Representatives.

4.1 Indenture, dated as of November 4, 2015, between the Issuing Entity and BNYM, as Trustee and Trust Collateral Agent.

4.2 Amended and Restated Trust Agreement, dated as of November 4, 2015, between AFS SenSub and WTC, as Owner Trustee.

4.3 Sale and Servicing Agreement, dated as of November 4, 2015, among the Issuing Entity, AmeriCredit, as Servicer, AFS SenSub and BNYM, as Trust Collateral Agent.

10.1 Purchase Agreement, dated as of November 4, 2015, between AmeriCredit, as Seller, and AFS SenSub, as Purchaser.

10.2 Lockbox Account Agreement, dated as of November 4, 2015, among AmeriCredit, BNYM, as Trustee, and JPMorgan Chase, as Processor.

10.3 Lockbox Processing Agreement, dated November 4, 2015, among AmeriCredit, BNYM, as Trustee, and Regulus, as Processor.

10.7 Second Amended and Restated Servicing Agreement, dated as of January 1, 2006, between AmeriCredit and General Motors Financial of Canada, Ltd. (see Exhibit 4.4 to Form 8-K filed on March 8, 2006, in connection with Registration Statement No. 333-121120-06, which is incorporated by reference herein).

3

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: November 4, 2015

4

EXHIBIT INDEX

5