T1
|
Tier 1 |
The least stringent
emission standards |
TLEV
|
Transitional Low
Emission Vehicle |
More stringent than
Tier 1 standards for hydrocarbons (HC) |
LEV
|
Low Emission Vehicle
|
More stringent than
TLEV standards for both hydrocarbons (HC) and nitrogen oxides
(NOx) |
ULEV
|
Ultra Low Emission
Vehicle |
More stringent than
LEV standards for HC |
SULEV
|
Super Ultra Low Emission
Vehicle |
Even more stringent
standards than ULEV for both HC and NOx |
ZEV
|
Zero Emission Vehicle
|
The strictest emission
standard, permitting no emissions |