EPA is granting conditional interim approval of a State Implementation Plan (SIP) revision submitted by New Jersey. This revision establishes and requires the implementation of an enhanced inspection and maintenance (I/M) program in the State. There are two intended effects of this action. One effect is to give conditional approval to the State's proposed enhanced I/M program under section 110 of the Clean Air Act. The other intended effect is to grant interim approval incorporating provisions authorized by section 348 of the National Highway System Designation Act, where applicable, to last a period of 18 months. Application of section 348 may result in some program adjustments during the 18-month period to ensure efficacy of the I/M program is achieved.