The application of biomass-based carbon “biochar” in the direct air capture of automobile CO2 emissions was investigated due to its porous microstructure, low cost, high abundance, and reuse of industrial waste. A relatively large share of U.S. greenhouse gas emissions is a result of petroleum-based, CO2-emitting automobiles. CO2 capture, which uses a porous adsorbent material to prevent gas molecules from entering the atmosphere and warming the environment, provides a way to reduce these emissions. While biochar is widely used for carbon sequestration in agriculture, its use in post-combustion direct air capture has not been thoroughly studied, especially in an automotive exhaust application. Almond waste materials were selected for biochar production due to their potential for high CO2 capture capacity and their abundance as agricultural waste in California. After low-temperature controlled burning, or pyrolysis, of the almond hulls and shells, the resulting biochar was found to be competitive in surface area studies compared to biochar produced with other feedstocks. Its CO2 capture capacity was tested in isolated experiments in a lab environment, as well as in a direct application on a test vehicle’s emissions via a manufactured tailpipe attachment and exhaust gas analysis. This study demonstrates that the use of biochar adsorbents in a direct air capture setting is viable and can be explored with further iterations of the tailpipe attachment and material processing.