AMBAC ASSURANCE CORPORATION

EXHIBIT 4.3

AMBAC ASSURANCE CORPORATION

NOTE GUARANTY INSURANCE POLICY

Policy No. AB0762BE

AMBAC ASSURANCE CORPORATION, a Wisconsin domiciled stock insurance corporation (“Ambae” or the “Insurer”), in consideration of the payment of the insurance premium payable with respect hereto, hereby unconditionally and irrevocably guarantees, subject only to (i) proper presentation of a Notice in accordance with the terms of this Note Guaranty Insurance Policy (together with each and every endorsement, if any, hereto, the “Policy”) and (ii) the terms of the Policy, the payment to, or at the direction of, the Indenture Trustee, for the benefit of the Holders of the Insured Obligations, that portion of the Deficiency Amounts which are Due for Payment but are unpaid by reason of Nonpayment.

1. Definitions.

Capitalized terms used herein and not otherwise defined shall have the meaning assigned to them in the Insurance Agreement or, if not defined therein, in the Indenture, without giving effect to any subsequent amendment ‘or modification thereto unless such amendment or modification has been approved in writing by Ambac. For purposes of the Policy, the following terms shall have the following meanings:

“Affiliate” shall mean, with respect to any specified Person, any other Person controlling or controlled by or under common control with such specified Person. For the purposes of this definition, “control” when used with respect to any Person means the power to direct the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise; and the terms “controlling” and “controlled” have meanings correlative to the foregoing.

“Bankruptcy Code” shall mean Title 11 of the United States Code.

“Business Day” shall mean any day that is not a Saturday, a Sunday or a day on which banking institutions in the states of Delaware, California, Texas, Virginia or New York, or in the state in which the Corporate Trust Office of the Indenture Trustee is located, are authorized or obligated by law, executive order or government decree to be closed.

“Class A Notes” shall mean, collectively, the Class A-1 Notes, the Class A-2 Notes, the Class A-3 Notes and the Class A-4 Notes.

“COAF Party” shall mean any of the Issuer, the Originator, the Servicer, the Seller and any of their respective Affiliates.

“Collection Period” shall mean each calendar month (or, in the case of the initial Collection Period, the period commencing on the close of business on the Initial Cut-Off Date and ending on June 30, 2004) and the “related” Collection Period means, with respect to any Payment Date, the Collection Period preceding the month in which such Payment Date occurs.

“Due for Payment” shall mean, with respect to any Deficiency Amounts, such amount as is due and payable pursuant to the terms of the Indenture.

“Final Scheduled Payment Date” shall mean, with respect to (i) the Class A-1 Notes, the Payment Date occurring in May 2005, (ii) the Class A-2 Notes, the Payment Date occurring in August 2007, (iii) the Class A-3 Notes, the Payment Date occurring in July 2008 and (vi) the Class A-4 Notes, the Payment Date occurring in March 2011.

“Holder” shall mean any registered or beneficial owner of a Class A Note (other than a COAF Party).

“Indenture” shall mean that certain Indenture, dated as of May 25, 2004, by and between the Issuer and the Indenture Trustee.

“Indenture Trustee” shall mean JPMorgan Chase Bank, not in its individual capacity but as trustee under the Indenture, and its successors and assigns in such capacity.

“Insurance Agreement” shall mean that certain Insurance and Indemnity Agreement, dated as of May 25, 2004, among the Insurer, the Servicer, the Originator, the Seller, the Issuer and the Indenture Trustee, in regard to the Class A Notes, as such agreement may be amended, modified or supplemented from time to time.

“Insured Payments” shall mean, (i) with respect to any Payment Date, the aggregate amount actually paid by the Insurer to, or at the direction of, the Indenture Trustee in respect of Deficiency Amounts for such Payment Date and (ii) the aggregate amount of any Preference Amounts paid by the Insurer on any given Business Day.

“Insurer” shall mean Ambac, or any successor thereto, as issuer of this Policy.

“Interest Rate” shall mean, with respect to (i) the Class A-I Notes, 1.21% per annum, (ii) the Class A-2 Notes, 2.22% per annum, (iii) the Class A-3 Notes, 3.07% per annum and (vi) the Class A-4 Notes, LIBOR + 0.10% per annum.

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“Issuer” shall mean Capital One Auto Finance Trust 2004-A, a Delaware statutory trust.

“Late Payment Rate” shall mean the rate of interest as it is publicly announced by Citibank, N.A. at its principal office in New York, New York as its prime rate (any change in such prime rate of interest to be effective on the date such change is announced by Citibank, N.A.). plus 3%. The Late Payment Rate shall be computed on the basis of a year of 365 days calculating the actual number of days elapsed. In no event shall the Late Payment Rate exceed the maximum rate permissible under any applicable law limiting interest rates.

“Maximum Insured Amount” shall mean $1,000,000,000 in respect of principal, plus interest thereon calculated at the applicable Interest Rate for each Class of Class A Notes.

“Nonpayment” shall mean, with respect to any Payment Date, Deficiency Amounts which are Due for Payment but have not been paid pursuant to the Indenture.

“Noteholders’ Interest Carryover Shortfall” means, with respect to any Payment Date, the excess of the sum of the Noteholders’ Monthly Accrued Interest for the preceding Payment Date and any outstanding Noteholders’ Interest Carryover Shortfall on such preceding Payment Date, over the amount in respect of interest that is actually paid to Noteholders on such preceding Payment Date, plus interest on the amount of interest due but not paid to Noteholders on the preceding Payment Date, to the extent permitted by law, at the respective Interest Rates borne by such Notes for the related Interest Period.

“Noteholders’ Parity Deficit Amount” means, with respect to any Payment Date, an amount equal to the excess, if any, of (i) the Note Balance of the Class A Notes as of such Payment Date (before application of all payments in respect of principal on such date); over (ii) the sum of (x) the amount of the Pool Balance (as of the last day of the related Collection Period) and (y) the amount on deposit in the Pre-Funding Account (as of the last day of the related Collection Period).

“Notice” shall mean the telephonic or telegraphic notice, promptly confirmed in writing by telecopy substantially in the form of Exhibit A or Exhibit B, as applicable, to this Policy, the original of which is subsequently delivered by registered or certified mail, from the Indenture Trustee specifying the amount of any Insured Payment which shall be due and owing.

“Order” shall have the meaning given such term in Section 8 hereto.

“Payment Date” shall mean the 15th day of each month during which any Class A Notes remain Outstanding (provided if any such date is not a Business Day, then the Payment Date shall be the next succeeding Business Day) beginning on July 15, 2004.

“Person” shall mean any individual, corporation, limited liability company, estate, partnership, joint venture, association, joint stock company, trust (including any beneficiary thereof), unincorporated organization or government or any agency or political subdivision thereof.

“Preference Amount” shall mean any interest on or principal of the Class A Notes which has become Due for Payment, the Nonpayment of which would have been covered by the Policy, and which was made to a Holder by or on behalf of the Issuer which has been deemed a preferential transfer and recoverable, or theretofore recovered, from its Holder pursuant to the Bankruptcy Code in accordance with a final, nonappealable order of a court of competent jurisdiction; provided that any Preference Amount that constitutes interest shall be limited to the amount of interest on the Note Balance of the Class A Notes (calculated at the Interest Rate for the relevant class of Class A Notes) accrued as of the last day of the applicable interest accrual period with respect to the Class A Notes and shall not, in any

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event, include any interest on the Class A Notes accrued after such date or any interest on such interest amount; provided, further, that in no event shall Ambac be obligated to make any payment in respect to any Preference Amount to the extent that such payment, when added to all prior payments of Deficiency Amounts, would exceed the Maximum Insured Amount.

“Preference Payment Date” shall have the meaning given such term in Section 8 hereto.

“Reimbursement Amount” shall mean, as of any Payment Date, the sum of (x)(i) all Insured Payments paid by Ambac, but for which Ambac has not been reimbursed prior to such Payment Date, plus (ii) interest accrued on such Insured Payments not previously repaid calculated at the Late Payment Rate from the date the Indenture Trustee, or any other Person at its direction, received the related Insured Payments or the date such Insured Payments were made, (y) (i) all costs and expenses of Ambac in connection with any action, proceeding or investigation affecting the Issuer, the Trust Estate or the rights or obligations of Ambac hereunder or under the Transaction Documents including any judgment or settlement entered into affecting Ambac or Ambac’s interests plus (ii) interest on such amounts of the Late Payment Rate and (z) without duplication (i) any amounts then due and owing to Ambac under the Insurance Agreement or the Indenture plus (ii) interest on such amounts at the Late Payment Rate.

“Reserve Account” shall mean the account designated as such, established and maintained pursuant to Section 4.1 of the Sale and Servicing Agreement.

“Sale and Servicing Agreement” shall mean that certain Sale and Servicing Agreement dated as of May 25, 2004 by and among the Issuer, the Seller, Capital One Auto Finance, Inc., as servicer and JPMorgan Chase Bank, as indenture trustee.

“Scheduled Payments” shall mean, with respect to any Payment Date, an amount equal to the sum of (a) the Accrued Note Interest (not including any Noteholders’ Interest Carryover Shortfall that Ambac has made Insured Payments in respect of on a prior Payment Date) and the Noteholders’ Parity Deficit Amount for the related Payment Date and, without duplication, (b) if the related Payment Date is the Final Scheduled Payment Date for any class of Class A Notes, the Note Balance of such Class on such date; provided that Scheduled Payments shall not include (x) any portion of Accrued Note Interest due to Holders because the Notice in proper form was not timely received by Ambac, or (y) any portion of Accrued Note Interest due to Holders representing interest on any Noteholders’ Interest Carryover Shortfall accrued from and including the date of payment of the amount of such Noteholders’ Interest Carryover Shortfall pursuant to the Policy.

“Seller” means Capital One Auto Receivables, LLC, a Delaware limited liability company.

2. Payments under the Policy.

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3. Presentation of Notice of Non-Payment and Demand.

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4. Waiver. Ambac’s obligations to make payment under this Policy are irrevocable, absolute and unconditional, irrespective of the value, genuineness, validity, legality or enforceability of the Indenture or any other agreement or instrument referred to herein or therein, or any substitution, release or exchange of any other guarantee of or security for the amounts Due for Payment hereunder, and, to the fullest extent permitted by applicable law, Ambac hereby waives any legal or equitable defense to payment under this Policy, including fraud in the inducement or fraud in the fact. Ambac hereby expressly waives diligence, presentment, protest and any requirement that the Indenture Trustee exhaust any right, power or remedy or proceed against the Issuer, or against any other person under any other guarantee of, or security for, the Indenture, provided that the Indenture Trustee shall be required to deliver a Notice as contemplated by this Policy. None of the foregoing waivers shall prejudice any claim Ambac may have, including without limitation for Reimbursement Amounts, whether directly or as subrogee, subsequent to making such payment to the Indenture Trustee in accordance with this Policy.

5. Subrogation. Upon any payment hereunder, in furtherance and not in limitation of Ambac’s equitable right of subrogation and Ambac’s rights under the Insurance Agreement, Ambac will, to the extent of such payment by Ambac hereunder, be subrogated to the rights of any Holder to receive any and all amounts due in respect of the Insured Obligations as to which such Insured Payment was made, to the extent of any payment by Ambac under this Policy and Ambac will be a co-beneficiary of the Indenture Trustee’s lien under the Indenture.

6. Communications. All notices (including Notices), presentations, transmissions, deliveries and communications made by the Indenture Trustee to Ambac with respect to this Policy shall specifically refer to the number of this Policy and shall be made to Ambac at:

or to such other address, officer, telephone number or facsimile number as Ambac may designate to the Indenture Trustee from time to time.

7. Nature of the Obligations. Except as expressly provided herein, the obligations of Ambac under this Policy are irrevocable, absolute and unconditional.

8. Termination. This Policy and the obligations of Ambac hereunder shall terminate upon the earlier of:

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provided, however, that notwithstanding the occurrence of any of the foregoing events, the Insurer shall pay any Preference Amount when due to be paid pursuant to an Order referred to below, but in any event no earlier than the fifth Business Day following actual receipt by the Insurer of (i) a certified copy of the final, nonappealable order of a court or other body exercising jurisdiction to the effect that a Holder is required to return such Preference Amount paid during the term of this Policy because the payments of such amounts were avoided as a preferential transfer or otherwise rescinded or required to be restored by the Indenture Trustee or such Holder (the “Order”), (ii) an opinion of counsel satisfactory to the Insurer stating that the Order has been entered and is final and not subject to any stay, (iii) an assignment, in form and substance satisfactory to the Insurer, duly executed and delivered by such Holder and the Indenture Trustee, irrevocably assigning to the Insurer all rights and claims of the Indenture Trustee and such Holder relating to or arising under the Indenture or otherwise with respect to such Preference Amount, (iv) appropriate instruments in form satisfactory to, the Insurer to effect the appointment of the Insurer as agent for the Indenture Trustee and such Holder in any legal proceeding related to such Preference Amount, and (v) a Notice (in the form attached as Exhibit B) appropriately completed and executed by the Indenture Trustee (the “Preference Payment Date”); provided, further, that (I) if such documents are received by the Insurer after 12:00 noon, New York City time, on such Business Day, they will be deemed to be received on the following Business Day, (II) the Insurer shall not be obligated to pay any Preference Amount in respect of principal (other than the Noteholders’ Party Deficit Amount) prior to the Final Scheduled Payment Date for the relevant class of Class A Notes and (III) any Preference Amount that constitutes interest shall be limited to the amount of interest on the Note Balance of the Class A Notes (calculated at the Interest Rate for the relevant class of Class A Notes) accrued as of the last day of the applicable interest accrual period with respect to the Class A Notes and shall not, in any event, include any interest on the Class A Notes accrued after such date or any interest on such interest amount. Such payment shall be disbursed to the receiver, conservator, debtor-in-possession or trustee in bankruptcy named in the Order, and not to the Indenture Trustee or the Holder directly, unless the Indenture Trustee or the relevant Holder has made a payment of the Preference Amount to the court or such receiver, conservator, debtor-in possession or trustee in bankruptcy named in the Order, in which case the Insurer will pay the Indenture Trustee, or as directed by the Indenture Trustee, to the extent of the payment of the Preference Amount, subject to the delivery of (a) the items referred to in clauses (i), (ii), (iii), (iv) and (v) above to the Insurer and (b) evidence satisfactory to the Insurer that payment has been made to such court or receiver, conservator, debtor-in-possession or trustee in bankruptcy named in the Order.

Notwithstanding the foregoing, in no event shall Ambac be obligated to make any payment in respect of any Preference Amount (i) to the extent that such payment, when added to all prior payments of Deficiency Amounts, would exceed the Maximum Insured Amount or (ii) prior to the time Ambac would have been required to make an Insured Payment pursuant to Section 3 of this Policy.

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9. There shall be no acceleration payment due under this Policy unless such acceleration is at the sole option of the Insurer. This Policy does not cover (i) premiums, if any, payable in respect of the Class A Notes, (ii) shortfalls, if any, attributable to any payment of withholding taxes (including penalties and interest in respect of any such liability) or (iii) any risk other than Nonpayment, including the failure of the Indenture Trustee to apply, disburse, transfer or direct Policy payments or Available Funds or other amounts in accordance with the Indenture to Holders or to any other party.

10. Miscellaneous.

ANY PERSON WHO KNOWINGLY AND WITH INTENT TO DEFRAUD ANY INSURANCE COMPANY OR OTHER PERSON FILES AN APPLICATION FOR INSURANCE OR STATEMENT OF CLAIM CONTAINING ANY MATERIALLY FALSE INFORMATION, OR CONCEALS FOR THE PURPOSE OF MISLEADING, INFORMATION CONCERNING ANY FACT MATERIAL THERETO, COMMITS A FRAUDULENT INSURANCE ACT, WHICH IS A CRIME AND SHALL ALSO BE SUBJECT TO A CIVIL PENALTY NOT TO EXCEED FIVE THOUSAND DOLLARS AND THE STATED VALUE OF THE CLAIM FOR EACH SUCH VIOLATION.

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IN WITNESS WHEREOF, Ambac has caused this Note Guaranty Insurance Policy to be executed and attested this 25th day of May, 2004.

Attest:

EXHIBIT A

TO THE NOTE GUARANTY INSURANCE POLICY

Policy No. AB0762BEa

NOTICE OF NONPAYMENT AND DEMAND FOR

PAYMENT OF INSURED AMOUNTS (OTHER

THAN PREFERENCE AMOUNT)

Date:                     

Ambac Assurance Corporation

One State Street Plaza

New York, New York 10004

Reference is made to Note Guaranty Insurance Policy No. AB0762BE (the “Policy”) issued by Ambac Assurance Corporation (“Ambac”). Terms capitalized herein and not otherwise defined shall have the meanings specified in the Policy, unless the context otherwise requires.

The undersigned hereby certifies as follows:

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ANY PERSON WHO KNOWINGLY AND WITH INTENT TO DEFRAUD ANY INSURANCE COMPANY OR OTHER PERSON FILES AN APPLICATION FOR INSURANCE OR STATEMENT OF CLAIM CONTAINING ANY MATERIALLY FALSE INFORMATION, OR CONCEALS FOR THE PURPOSE OF MISLEADING, INFORMATION CONCERNING ANY FACT MATERIAL THERETO, COMMITS A FRAUDULENT INSURANCE ACT, WHICH IS A CRIME AND SHALL ALSO BE SUBJECT TO A CIVIL PENALTY NOT TO EXCEED FIVE THOUSAND DOLLARS AND THE STATED VALUE OF THE CLAIM FOR EACH SUCH VIOLATION.

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EXHIBIT B

TO THE NOTE GUARANTY INSURANCE POLICY

Policy No. AB0762BE

NOTICE OF NONPAYMENT AND DEMAND FOR

PAYMENT OF PREFERENCE AMOUNT

Date:                    

Ambac Assurance Corporation

One State Street Plaza

New York, New York 10004

Reference is made to Note Guaranty Insurance Policy No. AB0762BE (the “Policy”) issued by Ambac Assurance Corporation (“Ambac”). Terms capitalized herein and not otherwise defined shall have the meanings specified in the Policy, unless the context otherwise requires.

The undersigned hereby certifies as follows:

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Preference Amount, (b) not apply such funds for any other purpose, and (c) maintain an accurate record of such payments with respect to the Class A Notes and the corresponding claim on the Policy and proceeds thereof.

ANY PERSON WHO KNOWINGLY AND WITH INTENT TO DEFRAUD ANY INSURANCE COMPANY OR OTHER PERSON FILES AN APPLICATION FOR INSURANCE OR STATEMENT OF CLAIM CONTAINING ANY MATERIALLY FALSE INFORMATION, OR CONCEALS FOR THE PURPOSE OF MISLEADING, INFORMATION CONCERNING ANY FACT MATERIAL THERETO, COMMITS A FRAUDULENT INSURANCE ACT, WHICH IS A CRIME AND SHALL ALSO BE SUBJECT TO A CIVIL PENALTY NOT TO EXCEED FIVE THOUSAND DOLLARS AND THE STATED VALUE OF THE CLAIM FOR EACH SUCH VIOLATION.

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