Exhibit 31.1



I, Susan B. Sheffield, certify that:



| | 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 GM Financial Consumer Automobile
Receivables Trust 2018-3 (the “Exchange Act periodic reports”);
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| | 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;
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| | 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;
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| | 4. | Based on my knowledge and 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 agreements in
all material respects; and
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| | 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.
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In giving the certifications above, I have reasonably relied
on information provided to me by the following unaffiliated parties: The Bank of New York Mellon.



|By:    | /s/ Susan B. Sheffield                               | 
|------ | ---------------------------------------------------- | 
|Name:  | Susan B. Sheffield                                   | 
|Title: | Executive Vice President and Chief Financial Officer | 
|Date:  | March 6, 2020                                        |