Overview
- The peer‑reviewed paper published July 16–17, 2026 analyzed more than 120 million real‑world trips and used vehicle‑specific energy models to estimate national impacts.
- Researchers estimate that if light‑duty gasoline vehicles stayed at posted limits the U.S. would save roughly 6.7–7.2 million gallons of fuel and about 57,000 tonnes of CO2 per day, worth about $22 million at 2021 prices and about $26 million using 2026 pump prices.
- Speeding is widespread in the sample: 43% of trips included at least one speeding event and drivers spent nearly 12% of driving time above posted limits, yet typical daily time saved by speeding is only about 54 seconds.
- The fuel penalty grows because air resistance rises sharply with speed, and limited California modeling in the study shows lower speeds also improve electric‑vehicle efficiency.
- Authors note key limits and next steps: slower driving could change traffic flow, the study did not fully capture aggressive acceleration or all roadway types, and the team plans instrumented EV tests and broader sampling to refine estimates.