U.S. Light and Medium Vehicle Emissions Regulations Tier 4 (I)

In April 2024, the United States Environmental Protection Agency (EPA) issued the Multiple Pollutant Emission Standards for Light and Medium Light Vehicles of 2027 and Later. Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium-Duty Vehicles), known as the Tier 4 emissions regulation, which will begin in 2027. The regulation focuses mainly on the setting of emission requirements. This topic provides a brief summary of the regulation and summarizes it in the form of emission cycles to provide a clearer reference for everyone.

1

Introduction of acronyms

 

GVWR : Gross Vehicle Weight Rating , equal to （ curb weight + maximum load ） .

LVW: Loaded Vehicle Weight, equal to (Ready Mass + 300 lbs).

ALVW：Adjusted Loaded Vehicle Weight，等于（整备质量+ GVW)/2。

LDV：Light Duty Vehicle， Refers to the number of passengers less than or equal to 12 passenger cars.

LDT：Light D uty Truc k，GVW Motor vehicles weighing less than or equal to 8,500 pounds and having a gross vehicle weight rating of less than or equal to 6,000 pounds, including vehicles carrying cargo or passengers （greater than 12 persons） or non-road vehicles.

MDPV: Medium Duty Passenger vehicles ，Medium passenger car.MDPVs have a gross vehicle weight rating （GVWR） of 8,501 to 14,000 pounds, but are primarily designed for passenger transportation and follow light vehicle standards .

MDVs:Medium Duty Vehicles, MDV The regulatory definition includes large pickup trucks, vans, and vehicles with a gross vehicle weight of 8,501 to 14,000 pounds, excluding MDPV.

2

Vehicle Classification

The U.S. vehicle classification for Tier 4 emissions regulations is shown in the table below .

3

Bin architecture

Following the release of the first edition, the Alliance for Automotive Innovation （AAI） and General Motors （GM） suggested that the EPA should align the classification structure with the ACCII program implemented by the California Air Resources Board （CARB）。 In addition, AAI proposed adding a new grading of 35, 45 and 90. Meanwhile, some small-scale manufacturers are calling for a model year in 2035 (MY 2035） before, continue to retain the points level of 125 access rights。 Based on this feedback, the EPA has adopted a full bin architecture, as detailed in the following table.

Bin number	NMOG+NO X (mg/mile)	Applicable models
Bin 170	170	MDVs only
Bin 150	150
Bin 125	125
Bin 100	100
Bin 85	85
Bin 75	75
Bin 70	70	LDV 、 LDT1 、 LDT2 、 LDT3 、 LDT4 、 MDPV
Bin 65	65
Bin 60	60
Bin 55	55
Bin 50	50
Bin 45	45
Bin 40	40
Bin 35	35
Bin 30	30
Bin 25	25
Bin 20	20
Bin 15	15
Bin 10	10
Bin 5	5
Bin 0	0

 

4

Fleet Average NMOG + NOX Limits

For 25°C FTP 、 H FET、US 06 And SC03'sN MO G + NOx limit standard :

Small volume criteria:

5

25C FTP emission limits

The 25C FTP emission limit values (same as high and low elevations) are shown in the table below.

	NMOG+NOx [mg/mil]	CO  [mg/mile]	PM [mg/mile]	HCHO [mg/mile]
LD	Depends on the selected Bin level	1700	0.5	4
MDVs		3200	0.5	6

 

6

-7C FTP emission limits

-7 ° C FTP emission limits are shown in the table below .

	NM HC+NOx  [mg/mil]	CO  [mg/mile]	PM [mg/mile]
LD	300	1 00 00	0.5
MDVs		100 00	0.5

 

7

US06 Emission Limits

The US06 emission limits are shown in the table below.

	NMOG+NOx [mg/mil]	CO  [mg/mile]	PM [mg/mile]
LD	Depends on the selected Bin level	9600	0.5
MD		250 00	0.5

 

8

SC03 Emission Limits

The SC03 emission limits are shown in the table below.

	NMOG+NOx [mg/mil]	CO  [mg/mile]
LD	Depends on the selected Bin level	1700
MD		32 00

 

9

HFET emission limits

The HFET cycle is primarily designed to test CO2, but must also meet requirements for NMOG + NOx and CO 。 Requirements for CO2 will be presented in a separate topic and are not listed here.

	NMOG+NOx [mg/mil]	CO  [mg/mile]
LD	Depends on the selected Bin level	1 7 00
MD		32 00