; (C) engine idle and parasitic energy loss reduction; (D) advanced internal combustion engines; and (E) engine down speeding; (2) electric drive trains, including— (A) durable highly efficient power electronics and electric machinery research; (B) partial load efficiency improvements; (C) control and coordination research for electric drive systems using multiple electric motors; (D) regenerative braking to recoup braking energy; and (E) high fidelity modeling to accelerate design and adoption of electrified commercial vehicles; (3) friction and wear reduction; (4) improved aerodynamics and tire rolling resistance; (5) advanced lightweighting materials and vehicle designs; (6) synthetic fuels from recycled CO 2 and other net-zero carbon liquid fuels; (7) vehicle batteries, including— (A) complete vehicle and battery pack modeling, simulation, and testing; and (B) thermal management of battery systems; (8) mild hybrid, heavy hybrid, plug-in hybrid, and electric platforms, and energy storage technologies, including— (A) identifying and developing solutions for technical barriers to advance batteries; (B) electric drive systems; and (C) charging and refueling systems for medium-duty goods and heavy-duty freight delivery vehicles; (9) vehicle components, including— (A) transmission and drivetrain optimization, including compact and efficient electric drivetrain systems; (B) waste heat recovery and conversion; (C) electrification of steering systems, braking systems, and accessory loads; (D) onboard sensing, computing, and communications technologies; and (E) advanced battery protection systems for safe handling of high voltage power; (10) relevant infrastructure, including bidirectional capability, beyond megawatt charging, and increasing load capacity per vehicle; (11) recharging infrastructure and compressed natural gas infrastructure; (12) hydrogen vehicle technologies, including— (A) fuel cells; (B) hydrogen fueling infrastructure