PURCHASE AGREEMENT

Exhibit 10.1

EXECUTION COPY

PURCHASE AGREEMENT

dated as of August 30, 2005

between

CAPITAL ONE AUTO FINANCE, INC.

and

CAPITAL ONE AUTO RECEIVABLES, LLC,

as Purchaser

TABLE OF CONTENTS

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TABLE OF CONTENTS

(continued)

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THIS PURCHASE AGREEMENT is made and entered into as of August 30, 2005 (as amended from time to time, this “ Agreement ”) by CAPITAL ONE AUTO FINANCE, INC., a Texas corporation (“ COAF ”), and CAPITAL ONE AUTO RECEIVABLES, LLC, a Delaware limited liability company (the “ Purchaser ”).

WITNESSETH:

WHEREAS, the Purchaser desires to purchase from COAF a portfolio of motor vehicle receivables, including motor vehicle retail installment loans that are secured by new and used automobiles, light-duty trucks and motorcycles; and

WHEREAS, COAF is willing to sell such portfolio of motor vehicle receivables and related property to the Purchaser on the terms and conditions set forth in this Agreement.

NOW, THEREFORE, in consideration of the premises and the mutual agreements set forth herein, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS AND USAGE

SECTION 1.1 Definitions . Except as otherwise defined herein or as the context may otherwise require, capitalized terms used but not otherwise defined herein are defined in Appendix A to the Sale and Servicing Agreement dated as of the date hereof (as from time to time amended, supplemented or otherwise modified and in effect, the “ Sale and Servicing Agreement ”) between Capital One Prime Auto Receivables Trust 2005-1, COAF, as Servicer, the Purchaser, as Seller, and JPMorgan Chase Bank, N.A., as Indenture Trustee, which also contains rules as to usage that are applicable herein. As used herein, the following terms shall have the following meanings:

“ Initial Purchased Assets ” has the meaning specified in Section 2.1 .

“ Purchased Assets ” has the meaning specified in Section 2.2 .

“ Subsequent Purchased Assets ” has the meaning specified in Section 2.2 .

SECTION 1.2 Other Interpretive Provisions . For purposes of this Agreement, unless the context otherwise requires: (a) accounting terms not otherwise defined in this Agreement, and accounting terms partly defined in this Agreement to the extent not defined, shall have the respective meanings given to them under generally accepted accounting principles; (b) terms defined in Article 9 of the UCC as in effect in the relevant jurisdiction and not otherwise defined in this Agreement are used as defined in that Article; (c) the words “hereof,” “herein” and “hereunder” and words of similar import refer to this Agreement as a whole and not to any particular provision of this Agreement; (d) references to any Article, Section, Schedule, Appendix or Exhibit are references to Articles, Sections, Schedules, Appendices and Exhibits in or to this Agreement and references to any paragraph, subsection, clause or other subdivision within any Section or definition refer to such paragraph, subsection, clause or other subdivision of such Section or definition; (e) the term “including” means “including without limitation”;

(f) except as otherwise expressly provided herein, references to any law or regulation refer to that law or regulation as amended from time to time and include any successor law or regulation; (g) references to any Person include that Person’s successors and assigns; and (h) headings are for purposes of reference only and shall not otherwise affect the meaning or interpretation of any provision hereof.

ARTICLE II

PURCHASE

SECTION 2.1 Agreement to Sell and Contribute on the Closing Date . On the terms and subject to the conditions set forth in this Agreement, COAF does hereby irrevocably sell, transfer, assign and otherwise convey to the Purchaser without recourse (subject to the obligations herein) on the Closing Date all of its right, title and interest in, to and under the Receivables, the Collections after the Initial Cut-Off Date, the Receivable Files and the Related Security relating thereto, whether now owned or hereafter acquired, identified in an Assignment substantially in the form of Exhibit A delivered on the Closing Date (collectively, the “ Initial Purchased Assets ”). The sale, transfer, assignment and conveyance made hereunder does not constitute and is not intended to result in an assumption by the Purchaser of any obligation of COAF or any Originator to the Obligors or any other Person in connection with the Receivables or the other assets and properties conveyed hereunder or any agreement, document or instrument related thereto.

SECTION 2.2 Agreement to Sell and Contribute on the Funding Dates . On the terms and subject to the conditions set forth in this Agreement, COAF does hereby sell, transfer, assign and otherwise convey to the Purchaser on each Funding Date all of its right, title and interest in, to and under the Receivables, and the Collections after the related Subsequent Cut-Off Date and the Related Security relating thereto, whether now owned or hereafter acquired, identified in an Assignment substantially in the form of Exhibit A delivered on such Funding Date (collectively, the “ Subsequent Purchased Assets ” and, together with the Initial Purchased Assets and all proceeds of the foregoing, the “ Purchased Assets ”). The sale, transfer, assignment and conveyance made hereunder does not constitute and is not intended to result in an assumption by the Purchaser of any obligation of COAF or any Originator to the Obligors or any other Person in connection with the Receivables or the other assets and properties conveyed hereunder or any agreement, document or instrument related thereto.

SECTION 2.3 Consideration and Payment . In consideration of the sale of the Initial Purchased Assets sold to the Purchaser on the Closing Date, the Purchaser shall pay to COAF on such date an amount equal to $1,165,021,246.83, representing the estimated fair market value of the Initial Purchased Assets on the Closing Date. Notwithstanding the preceding sentence, if such purchase price for the Initial Purchased Assets exceeds the amount of cash available to the Purchaser from the proceeds of the sale of the Notes, then an undivided interest in such Initial Purchased Assets in an amount equal to such excess shall be deemed to have been contributed to the Purchaser by COAF.

SECTION 2.4 Consideration and Payment for the Subsequent Purchased Assets . In consideration of the sale of the Subsequent Purchased Assets sold to the Purchaser on each

Funding Date, the Purchaser shall pay to COAF on such date an amount equal to the estimated fair market value of the related Subsequent Purchased Assets on such Funding Date (the “ Purchase Price ”). Notwithstanding the preceding sentence, if the Purchase Price to be paid by the Purchaser for such Subsequent Transferred Assets exceeds the amount of any cash payments paid by the Issuer to the Purchaser on such Funding Date for such Subsequent Transferred Assets, then an undivided interest in such Subsequent Transferred Assets in an amount equal to such excess shall be deemed to have been contributed to the Purchaser by COAF.

ARTICLE III

REPRESENTATIONS, WARRANTIES AND COVENANTS

SECTION 3.1 Representations and Warranties of COAF . COAF makes the following representations and warranties as of the Closing Date and as of each Funding Date on which the Purchaser will be deemed to have relied in acquiring the Purchased Assets. The representations and warranties will survive the conveyance of the Purchased Assets to the Purchaser, the conveyance of the Purchased Assets to the Issuer pursuant to the Sale and Servicing Agreement and the pledge thereof by the Issuer to the Indenture Trustee pursuant to the Indenture:

(a) Existence and Power . COAF is a corporation validly existing and in good standing under the laws of its state of organization and has, in all material respects, full power and authority to own its assets and operate its business as presently owned or operated, and to execute, deliver and perform its obligations under the Transaction Documents to which it is a party or affect the enforceability or collectibility of the Receivables or any other part of the Purchased Assets. COAF has obtained all necessary licenses and approvals in each jurisdiction where the failure to do so would materially and adversely affect the ability of COAF to perform its obligations under the Transaction Documents or affect the enforceability or collectibility of the Receivables or any other part of the Purchased Assets.

(b) Authorization and No Contravention . The execution, delivery and performance by COAF of the Transaction Documents to which it is a party have been duly authorized by all necessary action on the part of COAF and do not contravene or constitute a default under (i) any applicable law, rule or regulation, (ii) its organizational documents or (iii) any material indenture or material agreement or instrument to which COAF is a party or by which its properties are bound (other than violations of such laws, rules, regulations, indentures or agreements which do not affect the legality, validity or enforceability of any of such agreements and which, individually or in the aggregate, would not materially and adversely affect the transactions contemplated by, or COAF’s ability to perform its obligations under, the Transaction Documents).

(c) No Consent Required . No approval or authorization by, or filing with, any Governmental Authority is required in connection with the execution, delivery and performance by COAF of any Transaction Document other than (i) UCC filings, (ii) approvals and authorizations that have previously been obtained and filings that have previously been made and (iii) approvals, authorizations or filings which, if not obtained or made, would not have a material adverse effect on the enforceability or collectibility of the Receivables or any other part of the Purchased Assets or would not materially and adversely affect the ability of COAF to perform its obligations under the Transaction Documents.

(d) Binding Effect . Each Transaction Document to which COAF is a party constitutes the legal, valid and binding obligation of COAF enforceable against COAF in accordance with its terms, except as such enforceability may be limited by applicable bankruptcy, insolvency, reorganization, moratorium, receivership, conservatorship or other similar laws affecting the enforcement of creditors’ rights generally and, if applicable, the rights of creditors of limited liability companies from time to time in effect or by general principles of equity.

(e) No Proceedings . There are no actions, orders, suits or proceedings pending or, to the knowledge of COAF, threatened against COAF before or by any Governmental Authority that (i) assert the invalidity or unenforceability of this Agreement or any of the other Transaction Documents, (ii) seek to prevent the issuance of the Notes or the consummation of any of the transactions contemplated by this Agreement or any of the other Transaction Documents, (iii) seek any determination or ruling that would materially and adversely affect the performance by COAF of its obligations under this Agreement or any of the other Transaction Documents or have a material adverse effect on the Noteholders or (iv) relating to COAF that would materially and adversely affect the federal or Applicable Tax State income, excise, franchise or similar tax attributes of the Notes.

(f) Lien Filings . COAF is not aware of any material judgment, ERISA or tax lien filings against COAF.

SECTION 3.2 Representations and Warranties of COAF as to each Receivable . On the date hereof, with respect to the Initial Receivables, or on each Funding Date, with respect to the Subsequent Receivables, COAF hereby makes the representations and warranties set forth on Schedule I to the Sale and Servicing Agreement to the Purchaser as to the Initial Receivables and the Subsequent Receivables, as applicable, sold, transferred, assigned and otherwise conveyed to the Purchaser under this Agreement on which such representations and warranties the Purchaser relies in acquiring the Receivables. Such representations and warranties shall survive the sale of the Receivables to the Issuer under the Sale and Servicing Agreement, and the Grant of the Receivables by the Issuer to the Indenture Trustee pursuant to the Indenture. Notwithstanding any statement to the contrary contained herein or in any other Transaction Document, COAF shall not be required to notify any insurer with respect to any Insurance Policy obtained by an Obligor.

SECTION 3.3 Repurchase upon Breach . Upon discovery by or notice to the Purchaser or COAF of a breach of any of the representations and warranties described in Section 3.2 which materially and adversely affects the interests of the Issuer or the Noteholders, the party discovering such breach or receiving such notice shall give prompt written notice thereof to the other party; provided , that delivery of the Servicer’s Certificate shall be deemed to constitute prompt notice by the Servicer and the Issuer of such breach; provided, further, that the failure to give such notice shall not affect any obligation of COAF hereunder. If the breach materially and adversely affects the interests of the Purchaser, the Issuer or the Noteholders in such Receivable, then COAF shall either (a) correct or cure such breach or (b) repurchase such Receivable from

the Purchaser, in either case on or before the Payment Date following the end of the Collection Period which includes the 60th day after the date that COAF became aware or was notified of such breach. Any such breach or failure will not be deemed to have a material and adverse effect if such breach or failure does not affect the ability of the Purchaser (or its assignee) to receive and retain timely payment in full on such Receivable. Any such purchase by COAF shall be at a price equal to the Repurchase Price. In consideration for such repurchase, COAF shall make (or shall cause to be made) a payment to the Purchaser equal to the Repurchase Price by depositing such amount into the Collection Account prior to noon, New York City time on the date of such repurchase. Upon payment of such Repurchase Price by COAF, the Purchaser shall release and shall execute and deliver such instruments of release, transfer or assignment, in each case without recourse or representation, as may be reasonably requested by COAF to evidence such release, transfer or assignment or more effectively vest in COAF or its designee any Receivable and related Purchased Assets repurchased pursuant to this Section 3.3 . It is understood and agreed that the obligation of COAF to purchase any Receivable as described above shall constitute the sole remedy respecting such breach available to the Purchaser.

SECTION 3.4 Protection of Title .

(a) COAF shall authorize and file such financing statements and cause to be authorized and filed such continuation and other statements, all in such manner and in such places as may be required by law fully to preserve, maintain and protect the interest of the Purchaser under this Agreement in the Purchased Assets (other than any Purchased Assets with respect thereto, to the extent that the interest of the Purchaser therein cannot be perfected by the filing of a financing statement). COAF shall deliver (or cause to be delivered) to the Purchaser file-stamped copies of, or filing receipts for, any document filed as provided above, as soon as available following such filing.

(b) COAF shall not change its name, identity, corporate structure or jurisdiction of organization in any manner that would make any financing statement or continuation statement filed by COAF in accordance with paragraph (a) above “seriously misleading” within the meaning of Sections 9-506, 9-507 or 9-508 of the UCC, unless it shall have given the Purchaser at least five days’ prior written notice thereof and, to the extent necessary, shall have promptly filed amendments to previously filed financing statements or continuation statements described in paragraph (a) above.

(c) COAF shall give the Purchaser at least five days