(a) [Reserved]

(b) On-road testing. The performance standard shall include on-road testing (including out-of-cycle repairs in the case of confirmed failures) of at least 0.5% of the subject vehicle population, or 20,000 vehicles whichever is less, as a supplement to the periodic inspection required in paragraphs (f), (g), and (h) of this section. Specific requirements are listed in §51.371 of this subpart.

(c) On-board diagnostics (OBD). For those areas required to implement an enhanced I/M program prior to the effective date of designation and classifications under the 8-hour ozone standard, the performance standard shall include inspection of all model year 1996 and later light-duty vehicles and light-duty trucks equipped with certified on-board diagnostic systems, and repair of malfunctions or system deterioration identified by or affecting OBD systems as specified in §51.357, and assuming a start date of 2002 for such testing. For areas required to implement enhanced I/M as a result of designation and classification under the 8-hour ozone standard, the performance standard defined in paragraph (i) of this section shall include inspection of all model year 2001 and later light-duty vehicles and light-duty trucks equipped with certified on-board diagnostic systems, and repair of malfunctions or system deterioration identified by or affecting OBD systems as specified in §51.357, and assuming a start date of 4 years after the effective date of designation and classification under the 8-hour ozone standard.

(d) Modeling requirements. Equivalency of the emission levels which will be achieved by the I/M program design in the SIP to those of the model program described in this section shall be demonstrated using the most current version of EPA's mobile source emission model, or an alternative approved by the Administrator, using EPA guidance to aid in the estimation of input parameters. States may adopt alternative approaches that meet this performance standard. States may do so through program design changes that affect normal I/M input parameters to the mobile source emission factor model, or through program changes (such as the accelerated retirement of high emitting vehicles) that reduce in-use mobile source emissions. If the Administrator finds, under section 182(b)(1)(A)(i) of the Act pertaining to reasonable further progress demonstrations or section 182(f)(1) of the Act pertaining to provisions for major stationary sources, that NOX emission reductions are not beneficial in a given ozone nonattainment area, then NOX emission reductions are not required of the enhanced I/M program, but the program shall be designed to offset NOX increases resulting from the repair of HC and CO failures.

(e) [Reserved]

(f) High Enhanced Performance Standard. Enhanced I/M programs shall be designed and implemented to meet or exceed a minimum performance standard, which is expressed as emission levels in area-wide average grams per mile (gpm), achieved from highway mobile sources as a result of the program. The emission levels achieved by the State's program design shall be calculated using the most current version, at the time of submittal, of the EPA mobile source emission factor model or an alternative model approved by the Administrator, and shall meet the minimum performance standard both in operation and for SIP approval. Areas shall meet the performance standard for the pollutants which cause them to be subject to enhanced I/M requirements. In the case of ozone nonattainment areas subject to enhanced I/M and subject areas in the Ozone Transport Region, the performance standard must be met for both oxides of nitrogen (NOx) and volatile organic compounds (VOCs), except as provided in paragraph (d) of this section. Except as provided in paragraphs (g) and (h) of this section, the model program elements for the enhanced I/M performance standard shall be as follows:

(1) Network type. Centralized testing.

(2) Start date. For areas with existing I/M programs, 1983. For areas newly subject, 1995.

(3) Test frequency. Annual testing.

(4) Model year coverage. Testing of 1968 and later vehicles.

(5) Vehicle type coverage. Light duty vehicles, and light duty trucks, rated up to 8,500 pounds Gross Vehicle Weight Rating (GVWR).

(6) Exhaust emission test type. Transient mass-emission testing on 1986 and later model year vehicles using the IM240 driving cycle, two-speed testing (as described in appendix B of this subpart S) of 1981-1985 vehicles, and idle testing (as described in appendix B of this subpart S) of pre-1981 vehicles is assumed.

(7) Emission standards.

(i) Emission standards for 1986 through 1993 model year light duty vehicles, and 1994 and 1995 light-duty vehicles not meeting Tier 1 emission standards, of 0.80 gpm hydrocarbons (HC), 20 gpm CO, and 2.0 gpm NOX;

(ii) Emission standards for 1986 through 1993 light duty trucks less than 6000 pounds gross vehicle weight rating (GVWR), and 1994 and 1995 trucks not meeting Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, and 3.5 gpm NOX;

(iii) Emission standards for 1986 through 1993 light duty trucks greater than 6000 pounds GVWR, and 1994 and 1995 trucks not meeting the Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, and 3.5 gpm NOX;

(iv) Emission standards for 1994 and later light duty vehicles meeting Tier 1 emission standards of 0.70 gpm HC, 15 gpm CO, and 1.4 gpm NOX;

(v) Emission standards for 1994 and later light duty trucks under 6000 pounds GVWR and meeting Tier 1 emission standards of 0.70 gpm HC, 15 gpm CO, and 2.0 gpm NOX;

(vi) Emission standards for 1994 and later light duty trucks greater than 6000 pounds GVWR and meeting Tier 1 emission standards of 0.80 gpm HC, 15 gpm CO and 2.5 gpm NOX;

(vii) Emission standards for 1981-1985 model year vehicles of 1.2% CO, and 220 gpm HC for the idle, two-speed tests and loaded steady-state tests (as described in appendix B of this subpart S); and

(viii) Maximum exhaust dilution measured as no less than 6% CO plus carbon dioxide (CO2) on vehicles subject to a steady-state test (as described in appendix B of this subpart S); and

(viii) Maximum exhaust dilution measured as no less than 6% CO plus carbon dioxide (CO2) on vehicles subject to a steady-state test (as described in appendix B of this subpart S).

(8) Emission control device inspections.

(i) Visual inspection of the catalyst and fuel inlet restrictor on all 1984 and later model year vehicles.

(ii) Visual inspection of the positive crankcase ventilation valve on 1968 through 1971 model years, inclusive, and of the exhaust gas recirculation valve on 1972 through 1983 model year vehicles, inclusive.

(9) Evaporative system function checks. Evaporative system integrity (pressure) test on 1983 and later model year vehicles and an evaporative system transient purge test on 1986 and later model year vehicles.

(10) Stringency. A 20% emission test failure rate among pre-1981 model year vehicles.

(11) Waiver rate. A 3% waiver rate, as a percentage of failed vehicles.

(12) Compliance rate. A 96% compliance rate.

(13) Evaluation date. Enhanced I/M program areas subject to the provisions of this paragraph shall be shown to obtain the same or lower emission levels as the model program described in this paragraph by January 1, 2002 to within ±0.02 gpm. Subject programs shall demonstrate through modeling the ability to maintain this level of emission reduction (or better) through their attainment deadline for the applicable NAAQS standard(s).

(g) Alternate Low Enhanced I/M Performance Standard. An enhanced I/M area which is either not subject to or has an approved State Implementation Plan pursuant to the requirements of the Clean Air Act Amendments of 1990 for Reasonable Further Progress in 1996, and does not have a disapproved plan for Reasonable Further Progress for the period after 1996 or a disapproved plan for attainment of the air quality standards for ozone or CO, may select the alternate low enhanced I/M performance standard described below in lieu of the standard described in paragraph (f) of this section. The model program elements for this alternate low enhanced I/M performance standard are:

(1) Network type. Centralized testing.

(2) Start date. For areas with existing I/M programs, 1983. For areas newly subject, 1995.

(3) Test frequency. Annual testing.

(4) Model year coverage. Testing of 1968 and newer vehicles.

(5) Vehicle type coverage. Light duty vehicles, and light duty trucks, rated up to 8,500 pounds GVWR.

(6) Exhaust emission test type. Idle testing of all covered vehicles (as described in appendix B of subpart S).

(7) Emission standards. Those specified in 40 CFR part 85, subpart W.

(8) Emission control device inspections. Visual inspection of the positive crankcase ventilation valve on all 1968 through 1971 model year vehicles, inclusive, and of the exhaust gas recirculation valve on all 1972 and newer model year vehicles.

(9) Evaporative system function checks. None.

(10) Stringency. A 20% emission test failure rate among pre-1981 model year vehicles.

(11) Waiver rate. A 3% waiver rate, as a percentage of failed vehicles.

(12) Compliance rate. A 96% compliance rate.

(13) Evaluation date. Enhanced I/M program areas subject to the provisions of this paragraph (g) shall be shown to obtain the same or lower emission levels as the model program described in this paragraph by January 1, 2002 to within ±0.02 gpm. Subject programs shall demonstrate through modeling the ability to maintain this level of emission reduction (or better) through their attainment deadline for the applicable NAAQS standard(s).

(h) Ozone Transport Region Low-Enhanced Performance Standard. An attainment area, marginal ozone area, or moderate ozone area with a 1980 Census population of less than 200,000 in the urbanized area, in an ozone transport region, that is required to implement enhanced I/M under section 184(b)(1)(A) of the Clean Air Act, but was not previously required to or did not in fact implement basic I/M under the Clean Air Act as enacted prior to 1990 and is not subject to the requirements for basic I/M programs in this subpart, may select the performance standard described below in lieu of the standard described in paragraph (f) or (g) of this section as long as the difference in emission reductions between the program described in paragraph (g) and this paragraph are made up with other measures, as provided in §51.350(b)(5). Offsetting measures shall not include those otherwise required by the Clean Air Act in the areas from which credit is bubbled. The program elements for this alternate OTR enhanced I/M performance standard are:

(1) Network type. Centralized testing.

(2) Start date. January 1, 1999.

(3) Test frequency. Annual testing.

(4) Model year coverage. Testing of 1968 and newer vehicles.

(5) Vehicle type coverage. Light duty vehicles, and light duty trucks, rated up to 8,500 pounds GVWR.

(6) Exhaust emission test type. Remote sensing measurements on 1968-1995 vehicles; on-board diagnostic system checks on 1996 and newer vehicles.

(7) Emission standards. For remote sensing measurements, a carbon monoxide standard of 7.5% (with at least two separate readings above this level to establish a failure).

(8) Emission control device inspections. Visual inspection of the catalytic converter on 1975 and newer vehicles and visual inspection of the positive crankcase ventilation valve on 1968-1974 vehicles.

(9) Waiver rate. A 3% waiver rate, as a percentage of failed vehicles.

(10) Compliance rate. A 96% compliance rate.

(11) Evaluation date. Enhanced I/M program areas subject to the provisions of this paragraph shall be shown to obtain the same or lower VOC and NOx emission levels as the model program described in this paragraph (h) by January 1, 2002 to within ±0.02 gpm. Subject programs shall demonstrate through modeling the ability to maintain this level of emission reduction (or better) through their attainment deadline for the applicable NAAQS standard(s). Equality of substituted emission reductions to the benefits of the low enhanced performance standard must be demonstrated for the same evaluation date.

(i) Enhanced performance standard for areas designated and classified under the 8-hour ozone standard. Areas required to implement an enhanced I/M program as a result of being designated and classified under the 8-hour ozone standard, must meet or exceed the HC and NOX emission reductions achieved by the model program defined as follows:

(1) Network type. Centralized testing.

(2) Start date. 4 years after the effective date of designation and classification under the 8-hour ozone standard.

(3) Test frequency. Annual testing.

(4) Model year coverage. Testing of 1968 and newer vehicles.

(5) Vehicle type coverage. Light duty vehicles, and light duty trucks, rated up to 8,500 pounds GVWR.

(6) Emission test type. Idle testing (as described in appendix B of this subpart) for 1968-2000 vehicles; onboard diagnostic checks on 2001 and newer vehicles.

(7) Emission standards. Those specified in 40 CFR part 85, subpart W.

(8) Emission control device inspections. Visual inspection of the positive crankcase ventilation valve on all 1968 through 1971 model year vehicles, inclusive, and of the exhaust gas recirculation valve on all 1972 and newer model year vehicles.

(9) Evaporative system function checks. None, with the exception of those performed by the OBD system on vehicles so-equipped and only for model year 2001 and newer vehicles.

(10) Stringency. A 20% emission test failure rate among pre-1981 model year vehicles.

(11) Waiver rate. A 3% waiver rate, as a percentage of failed vehicles.

(12) Compliance rate. A 96% compliance rate.

(13) Evaluation date. Enhanced I/M program areas subject to the provisions of this paragraph (i) shall be shown to obtain the same or lower emission levels for HC and NOX as the model program described in this paragraph assuming an evaluation date set 6 years after the effective date of designation and classification under the 8-hour ozone standard (rounded to the nearest July) to within ±0.02 gpm. Subject programs shall demonstrate through modeling the ability to maintain this percent level of emission reduction (or better) through their applicable attainment date for the 8-hour ozone standard, also rounded to the nearest July.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 59 FR 32343, June 23, 1994; 60 FR 48035, Sept. 18, 1995; 61 FR 39036, July 25, 1996; 61 FR 40945, Aug. 6, 1996; 63 FR 24433, May 4, 1998; 65 FR 45532, July 24, 2000; 66 FR 18176, Apr. 5, 2001; 71 FR 17710, Apr. 7, 2006]