In this report, experts studied how introducing hydrogen cars can affect climate change in the U.S. They used a model called CarCarbon to predict what types of vehicles people will drive in the future, including hybrids, regular gas cars, and hydrogen-powered vehicles. By looking at factors like fuel prices and vehicle ownership trends, the model estimates how much fuel each type of vehicle will use and how much carbon dioxide they will emit in the next 25 years. The goal was to show how different cars and policies could impact energy consumption and emissions from vehicles.