In the US at least, efficiency improvements over the last decade or two have generally been offset by safety and performance improvements. Modern engines are mo

In the US at least, efficiency improvements over the last decade or two have generally been offset by safety and performance improvements. Modern engines are more efficient, but they're also more powerful and they're driving heavier vehicles that are more likely to keep you alive in a crash. Americans drive on highways a lot and the need to be able to accelerate through an on-ramp quickly enough to feel safe has lead to cars with less net fuel efficiency than we might have.