They are very picky about what is covered under the 8/80, most everything that's likely to fail is either in the 2/24 category or not covered at all.
From the EPA:
Design and Defect Warranty Coverage for 1995 and newer light-duty vehicles:
Emission control and emission related parts are covered for the first 2 years or 24,000 miles of vehicle use (whichever first occurs); and
Specified major emission control components are covered for the first 8 years or 80,000 miles of vehicle use (whichever first occurs).
EMISSION CONTROL PARTS
Exhaust Gas Conversion Systems: oxygen sensor, thermal reactor, catalytic converter, dual-walled exhaust pipe
Exhaust Gas Recirculation System: EGR valve, thermal vacuum switch, EGR solenoid, EGR spacer plate, EGR backpressure transducer, sensor and switches used to control EGR flow
Evaporative Emission Control System: purge valve, fuel filler cap, purge solenoid, vapor storage canister, and filter
Positive Crankcase Ventilation (PCV) System: PCV valve, PCV solenoid
Air Injection System: Air pump diverter, bypass, or gulp valve, reed valve, anti-backfire or deceleration valve
Early Fuel Evaporative (EFE) System: EFE valve, thermal vacuum switch, heat riser valve
Fuel Metering System: electronic control module (unit) or EFI air flow meter, computer command module or mixture control unit, deceleration controls, electronic choke, fuel injectors, fuel injection units and fuel altitude compensator sensor, bars or rails for EFI or TBI systems, mixture settings on sealed fuel mixture control solenoid, diaphragm or other systems, fuel metering components that achieve closed/other feedback control sensors/loop operation switches and valves
Air Induction System: thermostatically controlled air cleaner, air box
Ignition Systems: electronic spark advance timing advance/retard systems, high energy electronic ignition
Miscellaneous Parts: hoses, gaskets, brackets, clamps, and other accessories used in the above systems
EMISSION RELATED PARTS
These are examples of other parts of your vehicle which have a primary purpose other than emissions control but which nevertheless have significant effects on your vehicle's emissions. If any of these parts fail to function or function improperly, your vehicle's emissions may exceed federal standards. Therefore, when any of the parts of the following systems are defective in materials or workmanship and have failed in a way that would be likely to cause your vehicle's emissions to exceed federal standards, they should be repaired or replaced under the emissions warranty:
Fuel Injection System: fuel distributor
Air Induction System: turbocharger, intake manifold
Exhaust System: exhaust manifold
Ignition System: distributor, spark plugs, ignition wires and coil
Miscellaneous Parts: hoses, gaskets, brackets, clamps, and other accessories used in the above systems.
SPECIFIED MAJOR EMISSION CONTROL COMPONENTS:
There are three specified major emission control components, covered for the first 8 years or 80,000 miles of vehicle use (whichever first occurs) on 1995 and newer vehicles:
1. Catalytic converters.
2. The electronic emissions control unit or computer (ECU).
3. The onboard emissions diagnostic device or computer (OBD).