What speed is noted for increased fuel consumption in passenger cars and light trucks?

The correct answer is that increased fuel consumption in passenger cars and light trucks is noted at 75 mph.

Driving at higher speeds typically leads to increased aerodynamic drag, which forces the vehicle's engine to work harder to maintain that speed. This increase in resistance results in higher fuel consumption. Many studies and tests, including those conducted by automotive organizations and fuel economy experts, indicate that fuel efficiency tends to decline significantly as speed exceeds 60 mph, with marked declines occurring as speeds reach 70 mph and higher.

While lower speeds like 45 mph or 55 mph see better fuel efficiency, speeds around 65 mph are often within a more optimal range for many vehicles. However, the steep increase in fuel consumption is particularly notable at 75 mph due to the impact of increased wind resistance and engine load, thus making it a critical speed threshold to consider for efficient driving.