MTTC Upper Elementary (3–6) Science and Social Studies Practice Test 2026

The main idea is that how much fuel a car uses and how much exhaust it produces is largely set by how big the engine is. Engine size, or displacement, determines how much air and fuel can be burned in each engine cycle. A larger engine can move more air and thus burn more fuel to deliver higher power, especially during acceleration, which directly raises both fuel consumption and emissions. Other features like paint color or the number of doors don’t change how much fuel is burned in normal driving, and any effect from infotainment systems is small compared with the impact of engine size. So, engine size is the factor that most directly increases emissions and fuel use.