NOTE GUARANTY INSURANCE POLICY

E XHIBIT 4.3

AMBAC ASSURANCE CORPORATION

NOTE GUARANTY INSURANCE POLICY

Policy No. AB1061BE

AMBAC ASSURANCE CORPORATION, a Wisconsin domiciled stock insurance corporation (“Ambac” 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-A Notes, the Class A-3-B Notes and the Class A-4 Notes.

“ COAF Party ” shall mean any of the Issuer, the Originators, 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 February 28, 2007) 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 February 2008, (ii) the Class A-2 Notes, the Payment Date occurring in May 2010, (iii) the Class A-3-A Notes, the Payment Date occurring in August 2011, (iv) the Class A-3-B Notes, the Payment Date occurring in August 2011, and (v) the Class A-4 Notes, the Payment Date occurring in November 2013.

“ 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 February 15, 2007, by and between the Issuer and the Indenture Trustee.

“ Indenture Trustee ” shall mean The Bank of New York, 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 Agreement, dated as of February 28, 2007, 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.

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“ 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-1 Notes, 5.3212% per annum, (ii) the Class A-2 Notes, 5.33% per annum, (iii) the Class A-3-A Notes, 5.25% per annum, (iv) the Class A-3-B Notes, LIBOR +0.00% per annum and (v) the Class A-4 Notes, LIBOR +0.02% per annum.

“ Issuer ” shall mean Capital One Auto Finance Trust 2007-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 $1,500,000,000 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.

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“ 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 March 15, 2007.

“ 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 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, the Indenture, and the Sale and Servicing Agreement 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.

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“ Sale and Servicing Agreement ” shall mean that certain Sale and Servicing Agreement dated as of February 15, 2007 by and among the Issuer, the Seller, Capital One Auto Finance, Inc., as servicer and The Bank of New York, 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