To amend title 23, United States Code, with respect to the special rule for low emission and energy efficient vehicles facilities, and for other purposes.

HR 5321 extends the deadline for allowing low-emission and energy-efficient vehicles to use high-occupancy vehicle (HOV) lanes from September 30, 2025, to December 31, 2026. It also requires the Transportation Secretary to conduct a study within 180 days of enactment on whether electric vehicle exemptions in HOV lanes reduce traffic congestion, with results reported to Congress. The bill directly affects state and local transportation agencies managing HOV facilities and the Department of Transportation. Key provisions include the deadline extension and the mandated study, with no changes to vehicle eligibility rules.