LEUCADIA NATIONAL CORPORATION 315 Park Avenue South

Exhibit 10.4

LEUCADIA NATIONAL CORPORATION

315 Park Avenue South

New York, New York 10010

March 4, 2008,

as Amended and Restated on December 12, 2008

AmeriCredit Corp.

801 Cherry Street

Suite 3900

Fort Worth, Texas 76102

Attn: Daniel E. Berce, President and Chief Executive Officer

Ladies and Gentlemen:

We have discussed with you our intention to acquire shares of common stock, $0.01 par value per share (the “Common Stock”), of AmeriCredit Corp., a Texas corporation (the “Company”), and the possibility that the Company may enact certain shareholder protection measures. In consideration of your forbearing the enactment of such measures at the present time, and without prejudice to the Company’s enactment of such measures in the future, intending to be legally bound, we agree as follows:

1. We agree that, until March 3, 2010, without the prior approval of a majority of the members of the Board of Directors of the Company (the “Board”) who are not Associates or Affiliates of ours and who have not been nominated to serve on the Board by us or any of our Affiliates or Associates (the “Disinterested Directors”), we and our subsidiaries, Associates, Affiliates and any persons with whom we have formed a “group” (within the meaning of Section 13(d)(3) of the Exchange Act) (together, the “Restricted Persons”) will not (i) enter into or agree, offer or seek or propose to enter into, directly or indirectly, any merger, acquisition transaction or other business combination involving the Company or any of its subsidiaries or any of their respective assets or properties; (ii) make, or in any way participate in, directly or indirectly, any “solicitation” of “proxies” (as such terms are used in the proxy rules of the Securities and Exchange Commission promulgated under the Exchange Act) to vote, or seek to advise or influence any person with respect to the voting of, any voting securities of the Company or any of its subsidiaries in connection with seeking the removal of any directors on the Board or a change in the size or composition of the Board, or call a special shareholder’s meeting for any such purpose; or (iii) directly or indirectly enter into any discussions, negotiations, arrangements or understandings with any other person (including any individual, firm, corporation, partnership or other entity or any “person” as such term is used in Section 13(d) or Section 14(d)(2) of the Exchange Act) (“person”) with respect to any of the foregoing activities or propose any of such activities. The “Exchange Act” means the Securities Exchange Act of 1934, as amended, or any successor statute. The terms “Affiliate” and “Associate” shall have the meanings set forth in Rule 12b-2 of the General Rules and Regulations under the Exchange Act.

2. We acknowledge that the Restricted Persons have acquired more than 25% of the outstanding Common Stock and, until March 3, 2010, without the prior approval of a majority of the Disinterested Directors, we agree that the Restricted Persons will not acquire any additional shares of Common Stock (or rights in respect thereof) or the right or rights to vote additional voting securities of the Company, if as a result thereof, the Restricted Persons would have beneficial ownership (within the meaning of Section 13(d) of the Exchange Act) of in excess of 29.9% of the voting power of the Common Stock; provided, however, the Company agrees that if any other person, or group of which such other person is a part, that is unaffiliated with the Restricted Persons shall acquire more than 30% of the voting power of the Common Stock, then we shall be permitted to acquire such number of additional shares of Common Stock that would permit the Restricted Persons to beneficially own an aggregate amount of the Common Stock having voting power equal to the voting power of such other unaffiliated person, entity or group plus one percent (1%), such that the Restricted Persons are able to remain the largest holder of Common Stock by one percent (1%), unless (i) at such time there is no default or event of default under any of the Company’s or any of its subsidiaries’ warehouse credit facility agreements or securitization transaction agreements, and (ii) any such acquisition of additional Common Stock by the Restricted Persons would result in the occurrence of an event of default under any such agreement; provided further, however that the Restricted Persons may acquire additional shares of Common Stock (or rights in respect thereof) (a) pursuant to the exercise of the preemptive rights granted below or (b) in any rights offering conducted by the Company in which any current holders of the Company’s securities are offered the opportunity, on a pro rata basis, to acquire shares or other securities, voting or non-voting, of the Company, so long as (i) at the time of any such acquisition there is no default or event of default under any of the Company’s or any of its subsidiaries’ warehouse credit facility agreements or securitization transaction agreements, and (ii) any such acquisition of additional Common Stock or right or rights to acquire additional shares of Common Stock by the Restricted Persons would not result in the occurrence of a default or an event of default under any such agreement.

Preemptive Rights: The Company shall give you notice (an “Issuance Notice”) of any proposed issuance by the Company of any (i) Common Stock or other security with voting rights or (ii) securities exercisable or convertible into Common Stock or any other security with voting rights (collectively the items in (i) and (ii) being referred to as “New Securities”), in each case at least five (5) business days prior to the proposed issuance date. The Issuance Notice shall specify the price or prices at which such securities are to be issued, the form of consideration to be received by the Company and the other material terms of the issuance. Provided that such purchase by you would not result in a breach of any of your obligations under this letter agreement and the acquisition of the New Securities is permitted under the terms and conditions of this letter agreement, you shall be entitled to purchase up to your Pro Rata Share of the New Securities proposed to be issued, at the price or prices, on the terms and for the same form of consideration specified in the Issuance Notice (provided, however, that if the consideration to be received for such New Securities is not cash, the Board of Directors of the Company shall determine, in its reasonable judgment, the cash equivalent of such non-cash consideration and you shall be able to acquire your Pro Rata Share for cash). “Pro Rata Share” means the fraction that results from dividing (1) the number of shares of Common Stock owned by you (immediately before giving effect to the issuance) by (2) the number of shares of Common Stock owned by all of the Company’s stockholders (immediately before giving effect to the issuance). The Company shall have 90 days from the date of the Issuance Notice to consummate the

2

proposed issuance of any or all of such New Securities that you have not elected to purchase at the price and upon terms that are not materially less favorable to the Company than those specified in the Issuance Notice, provided that, if such issuance is subject to regulatory approval, such 90-day period shall be extended until the expiration of five (5) business days after all such approvals have been received, but in no event later than 180 days from the date of the Issuance Notice. If the Company proposes to issue any such Common Stock or other securities after such 90-day (or 180-day) period, it shall again comply with the procedures set forth in the Preemptive Rights provisions of this paragraph 2. Notwithstanding the foregoing, the term “New Securities” shall not include, and you shall not be entitled to purchase Common Stock or any other securities as contemplated by the Preemptive Rights provisions of this paragraph 2 in connection with (A) issuances of Common Stock or securities to officers or other employees of the Company in connection with such person’s employment with the Company or to members of the Company’s board of directors under any arrangement provided generally to directors for their service as directors of the Company, (B) issuances of Common Stock, rights, warrants, options and/or convertible or exchangeable securities in connection with any financing transaction, including, without limitation, senior or subordinated notes, securitizations or similar transactions, commercial bank or non-bank facilities, commitments or arrangements, bridge financing or back-stop facilities, commitments or arrangements, whole-loan purchase facilities, commitments or arrangements, forward purchase facilities, commitments or arrangements, or other similar facilities, commitments, arrangements or issuances of non-convertible debt obligations or securities, (C) any issuance that, if as a result of such shares of Common Stock or securities being issued to you, the Company would be required to seek shareholder approval prior to such issuance or seek an exemption from any applicable rules of the New York Stock Exchange or any other stock exchange on which the Common Stock of the Company is then listed; provided, however, that the limitation set forth in this clause (C) shall not apply if the Company is seeking shareholder approval prior to such issuance or seeking an exemption from any applicable rules of the New York Stock Exchange or any other stock exchange on which the Common Stock of the Company is then listed in connection with such issuance other than as a result of such shares of Common Stock or securities that would be issued to you, (D) the conversion or exchange of any of the Company’s preferred stock, warrants, options or other convertible or exchangeable securities, provided, such preferred stock, warrants, options or other convertible or exchangeable securities are outstanding as of the date of this letter agreement or were issued in connection with a transaction set out in the Preemptive Rights provisions of this paragraph 2, (E) a merger or consolidation of the Company with another corporation, partnership, limited liability company or business organization, or the acquisition of assets from any such entity, (F) any issuance of Common Stock or securities exercisable or convertible for Common Stock in exchange for the Company’s currently outstanding debt obligations (including any renewals, modifications, extensions, or restatements of currently outstanding debt obligations), (G) a rights offering conducted by the Company on a pro rata basis to the holders of Common Stock of the Company, or (H) any issuance by the Company of up to an aggregate of 5 million shares of Common Stock or securities exercisable or convertible into up to an aggregate of 5 million shares of Common Stock (or any combination thereof), in one or more transactions. The rights granted under the Preemptive Rights provisions of this paragraph 2 shall terminate and be of no further force or effect upon the termination of the restrictions and agreements contained in paragraphs 1 through 6 of this letter agreement in accordance with the terms of this letter agreement, and the rights granted under the Preemptive Rights provisions of this paragraph 2 shall not be exercisable by

3

you if the acquisition of New Securities upon the exercise of the rights granted under the Preemptive Rights provisions of this paragraph 2 is otherwise prohibited by the terms of this letter agreement. The rights granted to you under the Preemptive Rights provisions of this paragraph 2 may not be assigned by you without the prior written consent of the Company.

3. We agree that, until March 3, 2010, without the prior approval of a majority of the Disinterested Directors, the Restricted Persons will not sell or dispose, in a single transaction or series of transactions, Common Stock (or rights in respect thereof) to any other person or “group” if we know the person or group would hold (for such purpose, including the right to acquire), in excess of 4.9% of the Common Stock, unless (i) prior to such sale or disposition, the proposed transferee enters into an agreement with the Company in substantially the form of this letter agreement (other than Paragraph 6); (ii) such sale is part of a tender offer or exchange offer made to all stockholders of the Company by a person other than us or who is not a subsidiary or an Affiliate or Associate of ours and is not a part of a “group” of which we are a part; or (iii) such disposition is pursuant to a dividend or distribution made by us on a pro rata basis to our shareholders.

4. The restrictions set forth in Paragraph 2 hereof are expressly agreed to preclude us from engaging in any hedging or other transaction which is or would result in the acquisition of “beneficial ownership” (as defined in Rule 13d-3 of the Exchange Act) of Common Stock in contravention of the provisions of this letter agreement. Such prohibited hedging or other transactions would include, without limitation, any purchase, sale or grant of any right (including, without limitation, any put or call option) with respect to Common Stock or with respect to any security that includes, relates to, or derives any significant part of its value from such Common Stock.

5. We agree that, until March 3, 2010, at any meeting of the shareholders of the Company, however called, or in any other circumstance in which the vote, consent or approval of the shareholders of the Company, in their capacity as shareholders, is sought, with respect to the election of directors of the Company, that we shall vote or give our consent with respect thereto, or cause to be voted or consent to be given with respect thereto, all shares of Common Stock held by the Restricted Persons, or over which we exercise voting control, in favor of those nominees approved by the Disinterested Directors, provided, if we have become and remain entitled to designate individuals for election to the Board in accordance with Paragraph 6, that our nominees shall have been nominated to serve on the Board upon the expiration of their terms of office, if any such terms are expiring, to the extent required under Paragraph 6. We agree that we will not grant any proxy, power-of-attorney or other authorization in or with respect to any shares of Common Stock that are held by the Restricted Persons, or over which we exercise voting control, or take any other action, in our capacity as a shareholder of the Company, that would in any way restrict, limit or interfere with the performance of our obligations hereunder.

6. As a result of our acquisition of more than 25% of the outstanding Common Stock, the Company shall promptly increase the size of the Board by two (2) directorships, and the vacancies on the Board created thereby shall be filled by the Disinterested Directors with two of our designees to be selected by us in our sole discretion, who initially shall be Ian Cumming and Justin Wheeler. One of such designees shall be appointed to the class of directors whose term expires at the 2008 annual meeting of shareholders, and the other such designee shall be

4

appointed to the class of directors whose term expires at the 2009 annual meeting of shareholders. In each subsequent election of directors of the Company, the Company shall use its best efforts to nominate a slate such that, when taken together with the directors not then up for re-election, the Board will include two directors designated by us. If any of our director designees resigns or becomes ineligible to serve on the Board, we shall have the right, in our sole discretion, to designate a replacement for such director designee, provided such replacement is eligible to serve on the Board. Upon our request, one of our director designees shall be appointed to serve on each committee of the Board, provided that such designee is qualified to serve on such committee under applicable regulations and listing standards. The Company shall not increase the size of the Board beyond nine (9) directorships without the approval of both a majority of the members of the Board and our director designees. If, after having acquired beneficial ownership of at least 25% of Common Stock, we (including our subsidiaries, Associates and Affiliates) subsequently sell or otherwise dispose of shares of Common Stock and, as a result, we (including our subsidiaries, Associates and Affiliates) shall beneficially own less than 20% of the Common Stock, we shall cause the individuals designated by us then serving on the Board to resign from the Board if requested by the Disinterested Directors and, subject to the proviso below, we shall no longer be entitled to representation on the Board; provided, however, that if we purchase additional shares of Common Stock such that we again own 20% or more of the Common Stock within sixty (60) days of such request by the Disinterested Directors, the individuals designated by us then serving on the Board shall not be required to resign and we shall continue to be entitled to representation on the Board pursuant to this letter agreement.

7. The Company shall furnish us with such financial information concerning the Company that we request to enable us to timely comply with our reporting obligations under applicable securities laws.

8. The Company and we shall enter into a mutually acceptable registration rights agreement having the principal terms set forth on Annex A hereto affording us the right to require the Company, at the Company’s expense, to file with the Securities and Exchange Commission, upon our demand, a registration statement on Form S-3 registering the resale of the shares of Common Stock owned by us.

9. We agree that all shares of Common Stock that we beneficially own as of the date of this letter agreement, and any shares of Common Stock that we purchase or with respect to which we otherwise acquire beneficial ownership or voting rights, directly or indirectly, after the date of this letter agreement, including, without limitation, shares issued upon the conversion, exercise or exchange, as the case may be, of securities held by us that are convertible into, or exercisable or exchangeable for, shares of Common Stock, shall be subject to the terms and conditions of this letter agreement.

10. Except as otherwise provided herein, the restrictions and agreements made by us contained in Paragraphs 1 through 6 shall terminate upon the earliest to occur of (i) such time as the Restricted Persons own less than 5% of the Common Stock; (ii) the Company’s breach of any material provision of this Agreement, which breach shall continue uncured for more than 30 days after written notice of such breach shall have been delivered by us to the Disinterested Directors (but any such breach hereof by the Company shall not relieve the Company of the restrictions

5

and agreements made by it herein); (iii) the acquisition by any person or “group” that is not affiliated or associated with us of a majority of the Common Stock; (iv) the date on which the Company shall have entered into any merger, acquisition transaction or other business combination involving the Company or its assets or properties; (v) March 3, 2010; or (vi) the Company (a) commences any bankruptcy, reorganization, debt arrangement, or other case or proceeding under any state or federal bankruptcy or insolvency law, (b) applies for, consents to, or acquiesces in, the appointment of a trustee, receiver or other custodian for the Company or a substantial part of its property, or makes a general assignment for the benefit of creditors, under any state or federal bankruptcy or insolvency law, (c) has a trustee, receiver, or other custodian appointed for the Company or a substantial part of the Company’s property under any state or federal bankruptcy or insolvency law, or (d) has a bankruptcy, reorganization, debt arrangement, or other case or proceeding under any state or federal bankruptcy or insolvency law, that is involuntarily commenced against or in respect of the Company and which shall not have been dismissed within 30 days following the commencement thereof. The restrictions and obligations of the Company contained in Paragraphs 6 and 8 hereof shall terminate upon the earliest to occur of (i) if we breach any material provision of this letter agreement, which breach shall continue uncured for more than 30 days after written notice of such breach shall have been delivered by the Company to us, but any such breach hereof by us shall not relieve us of the restrictions and agreements made by us herein or (ii) March 3, 2010. Notwithstanding the foregoing, the provisions of Paragraph 7 hereof shall continue for so long as (but only to the extent that) we are required to include financial information concerning the Company in our public reporting).

11. The parties hereto acknowledge and agree that money damages would not be a sufficient remedy for any breach or threatened breach of any provision of this letter agreement, and that in addition to all other remedies which we or the Company may have, each of the parties hereto will be entitled to seek specific performance and injunctive or other equitable relief as a remedy for any such breach, without the necessity of posting any bond.

12. It is understood and agreed that no failure or delay by a party hereto in exercising any right, power or privilege hereunder shall operate as a waiver thereof, nor shall any single or partial exercise thereof preclude any other or further exercise thereof or the exercise of any right, power or privilege hereunder.

13. The invalidity or unenforceability of any provision of this letter agreement shall not affect the validity or enforceability of any other provisions of this letter agreement, which shall remain in full force and effect.

14. This letter agreement, including, without limitation, the provisions of this Paragraph 14, may not be amended, modified, terminated or waived, in whole or in part, except upon the prior written approval of a majority of the Disinterested Directors and by a separate writing signed by the Company, if so authorized by such Disinterested Directors, and us expressly so amending, modifying, terminating or waiving such agreement or any part hereof. Any such amendment, modification, termination or waiver of this letter agreement or any part hereof made without the prior written approval of such Disinterested Directors shall be void and of no legal effect.

6

15. This letter agreement may be executed in two or more counterparts (including by means of facsimile), each of which shall be deemed to be an original but all of which together shall constitute one and the same instrument. Receipt of an executed signature page to this letter agreement by facsimile or other electronic transmission shall constitute effective delivery thereof. Electronic records of this executed letter agreement shall be deemed to be originals thereof.

16. Each party agrees and consents to personal jurisdiction and service of process and exclusive venue in the federal district court for the Northern District of Texas, Dallas Division, of the State of Texas for the purposes of any action, suit or proceeding arising out of or relating to this letter agreement. This letter agreement shall be governed by, and construed in accordance with, the laws of the State of Texas, without regards to its conflicts of law principles.

17. This letter agreement, dated as of December 12, 2008, amends and restates in its entirety that certain letter agreement among the parties hereto, dated as of March 4, 2008.

Confirmed and agreed to as of

the date first written above:

7

Annex A

Terms of Registrations Rights Agreement