N.H. Rev. Stat. Ann. § 262:26

Nothing in this subdivision shall be construed as amending, modifying or repealing any existing law of New Hampshire or any existing ordinance of any political subdivision relating to the driving or licensing of vehicles, the licensing of persons to drive vehicles or providing penalties for the violation thereof; or shall be construed so as to preclude the exercise of the regulatory powers of any division, agency, department or political subdivision of the state having the statutory power to regulate such driving and licensing.