EXHIBIT 31

CERTIFICATION PURSUANT TO

Rule 15d-14(d)

I, Fritz D.
Bohne, certify that:

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| | 1. | I have
  reviewed this report on Form 10-K and all reports on Form 10-D required to be
  filed in respect of the period covered by this report on Form 10-K of USAA
  Auto Owner Trust 2006-4 (the Exchange Act periodic reports);                                                                                                                                                                                                                                                                                                                                                    
| |    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
| | 2. | Based on my
  knowledge, the Exchange Act periodic reports, taken as a whole, do not
  contain any untrue statement of a material fact or omit to state a material
  fact necessary to make the statements made, in light of the circumstances
  under which such statements were made, not misleading with respect to the
  period covered by this report;                                                                                                                                                                                                                             
| |    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
| | 3. | Based on my
  knowledge, all of the distribution, servicing and other information required
  to be provided under Form 10-D for the period covered by this report is
  included in the Exchange Act periodic reports;                                                                                                                                                                                                                                                                                                                                                                   
| |    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
| | 4. | I am
  responsible for reviewing the activities performed by the servicer and based
  on my knowledge and the compliance review conducted in preparing the servicer
  compliance statement required in this report under Item 1123 of Regulation
  AB, and except as disclosed in the Exchange Act periodic reports, the
  servicer has fulfilled its obligations under the servicing agreement in all
  material respects; and                                                                                                                                                         
| |    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
| | 5. | All of the
  reports on assessment of compliance with servicing criteria for asset-backed
  securities and their related attestation reports on assessment of compliance
  with servicing criteria for asset-backed securities required to be included
  in this report in accordance with Item 1122 of Regulation AB and Exchange Act
  Rules 13a-18 and 15d-18 have been included as an exhibit to this report,
  except as otherwise disclosed in this report. Any material instances of
  noncompliance described in such reports have been disclosed in this report on
  Form 10-K.

In giving the
certifications above, I have reasonably relied on information provided to me by
the following unaffiliated parties: The Bank of New York.

| |                                                  | 
| | ------------------------------------------------ | 
| | /s/ FRITZ D.
  BOHNE                             | 
|
| |                                                  | 
| | Name:  Fritz D. Bohne                            | 
| | Title:  Vice President, Senior Financial Officer | 

March 30, 2007

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