The "Shared Autonomous Mobility Act of 2026" aims to significantly advance the integration of autonomous shared mobility vehicles, primarily buses, into public transportation networks. It establishes a new federal grant program, the Accelerating Innovative Mobility Grant Program, providing competitive grants to eligible entities for projects deploying these advanced vehicles. These grants can cover the acquisition of autonomous buses, hardware, and software, including automated driving systems and their updates, with a federal share of up to 80 percent and a reservation of 15 percent of funds for rural projects. To ensure safety and performance, the bill mandates the establishment of dedicated testing facilities for covered shared mobility vehicles by January 1, 2027. These facilities will specifically test autonomous bus models for maintainability, reliability, and safety, complementing existing facilities for traditional buses. The Secretary of Transportation must also update bus testing standards and create a "pass/fail" scoring system for both traditional and autonomous bus models. Additionally, the legislation amends several existing federal transportation grant programs, such as the SMART and Buses and Bus Facilities grants. These amendments explicitly broaden the allowable uses of funds to include the acquisition, licensing, and updating of software for automated driving systems and the operation or monitoring of autonomous vehicles. This comprehensive approach seeks to remove financial and infrastructural barriers to the adoption of autonomous public transit.