Congressional Budget Office Cost Estimate: S. 747, Diesel Emissions Reduction Act of 2019 [open pdf - 0B]
"S. 747 would authorize the appropriation of $100 million annually through 2024 for the Environmental Protection Agency (EPA) to provide grants and rebates for projects and state programs that reduce emissions from diesel engines. The bill also would require EPA to provide guidance to states about technical differences in vehicles, engines, equipment, and vehicle fleet use. Finally, the bill would direct that funds not allocated to state diesel programs be reallocated to projects for retrofitting vehicles. In 2019, $87 million was appropriated for those purposes."
Congressional Budget Office: http://www.cbo.gov/