Inline-six engines were once a defining part of American automotive culture, known for their smooth power delivery and effortless torque. But in 2025, they’ve become nearly extinct. As automakers shift toward downsized turbo-fours, V-6s, and electrification to meet efficiency regulations, the classic straight-six has all but disappeared from mainstream lineups. What’s left is a tiny group of vehicles keeping this legendary layout alive, and most shoppers don’t realize how rare it’s become.