The results were clear : `` By and large , across the 50 states , there was no discernible effect from the higher limits , '' Yowell said . U.S. drivers face patchwork of speed limits across the nation . The National Highway Traffic Safety Administration has proposed a nationwide standard for cars that would require all new vehicles to have at least five miles per gallon by 2025 and an average fuel economy rating of 54.5 Some researchers skeptical of link between accidents , high speeds .
U.S. drivers face patchwork of speed limits across the nation . The National Highway Traffic Safety Administration has proposed a nationwide standard for cars that would require all new vehicles to have at least five miles per gallon by 2025 and an average fuel economy rating of 54.5 Some researchers skeptical of link between accidents , high speeds .