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 |