Have your students research vehicles to help them show mastery on solving systems of linear equations. The document provided is amendable to your tastes and provides you with a framework for a project that will get your students engaged and focused. Students will need to figure out which car is cheaper over the long-run based on the initial cost and gas cost per year. Information for solving the system of equations by graphing, elimination, and substitution is provided as well as a calculations page and analysis page.
If you want to download the rubric, please see my page for it.