Connecticut laws/regulations;

OLR Research Report

June 4, 2001






By: James J. Fazzalaro, Principal Research Analyst

You asked what types of vehicles are exempt from emissions testing and if this includes sport utility vehicles and all trucks. If these vehicles are exempt, you wanted to know the reason.

Although vehicles with gross weights over 10,000 pounds are among the exemptions from the emissions inspection program operated by the Envirotest, the state emissions contractor, neither sport utility vehicles nor trucks are exempt as a group.

The state essentially has two motor vehicle emissions inspection programs. The larger one is run for the state by Envirotest at 25 inspection locations. The other program applies exclusively to large diesel-powered commercial vehicles and is run by the Department of Motor Vehicles (DMV) as part of its Motor Carrier Safety Assistance Program. These inspections are performed by the DMV inspectors in conjunction with safety and weight inspections.


By law (CGS 14-164c), the following types of vehicles are exempt from the inspection program run by Envirotest:

1. Vehicles with gross weight ratings over 10,000 pounds;

2. Electric powered vehicles;

3. Motorcycles and bicycles with helper motors (mopeds);

4. Vehicles manufactured 25 or more years ago;

5. New vehicles at the time of initial registration;

6. Farm vehicles;

7. Vehicles registered but not designed primarily for highway use;

8. Vehicles under temporary registrations;

9. Diesel-powered Type II school buses (gross weight ratings up to 10,000 pounds); and

10. Vehicles operated by licensed dealers or repairers between their places of business and an inspection station for purposes of an emissions or safety inspection.

Public Act 00-180 added another potential exempt category. It requires the DMV emissions program regulations, by October 1, 2002, to exempt all vehicles up to four model years old as long as this does not violate federal environmental or transportation planning requirements. This exemption is not yet in effect.

Diesel powered motor vehicles, although once exempt from the emissions inspection program, are no longer exempt. But they are subjected to a different type of test than gasoline powered vehicles.

Sport utility vehicles and trucks as a group are not exempt, but some could possibly fall within one of the exempt categories noted above. Trucks over 10,000 pounds are exempt under the first exemption noted above ifthey are gasoline powered, but, depending on their use, could be subject to inspection under the large truck program if they are diesel powered. The main reason why vehicles larger than 10,000 pounds gross weight were exempted from inspections was the cost of installing heavy-duty dynamometers necessary for these larger vehicles compared to the number of vehicles requiring testing. It was considered too costly for the benefit that would be derived from testing this relatively small number of vehicles.

Some of the larger sport utility vehicles, vans, and pickup trucks are considered heavy-duty trucks rather than light duty trucks or vehicles under federal regulations and thus the emissions standards applied to them are different than for smaller vehicles like passenger cars.


Another law establishes the large diesel powered commercial vehicle inspection program (CGS 14-164i). It applies to diesel powered commercial vehicles which (1) are over 26,000 pounds gross weight rating, (2) are designed to transport 16 or more passengers, including the driver, or (3) transport hazardous materials required to be placarded under federal hazardous materials transportation regulations. School buses are not considered subject to inspection under this law (CGS 14-164i(h)). Vehicles are subjected to an emissions test in conjunction with any weight or safety inspections being conducted. A vehicle's exhaust smoke is subjected to an opacity test known as the “Snap Acceleration Test.” The density of the exhaust smoke is measured and opacity standards developed by the Department of Environmental Protection are applied based on the vehicle's age. 1991 and newer vehicles must meet a 40% opacity standard. Vehicles between 1990 and 1974 must meet a 55 % opacity standard. Vehicles that are 1973 and older must meet a 70% opacity standard.