For a heavy vehicle (GVWR over 8,500 pounds) registered in an Enhanced area, which emissions test is required?

• A. BAR Ref test
• B. TSI test
• C. Idle test
• D. Sniffer test

Answer: (B)

The test being used is the Two‑Speed Idle (TSI) test. For heavy vehicles (GVWR over 8,500 pounds) registered in Enhanced areas, this method is required because it measures emissions at two engine speeds—idle and a higher idle—to better represent real-world operation under different loads. This provides a more accurate picture of how the vehicle behaves in daily driving than a single idle measurement. The other tests aren’t the standard choice here: an idle-only test wouldn’t capture emissions at higher engine speeds; a sniffer test is not the mandated method for these heavy vehicles in Enhanced areas; and a BAR Ref test is reserved for cases that need referee involvement, not the routine requirement.