Which of the following can cause poor gasoline mileage?

Driving at high speeds can lead to poor gasoline mileage due to the increased air resistance and the engine working harder to maintain such speeds. When a vehicle is driven at high speeds, the aerodynamic drag on the car increases significantly. This means the engine needs to burn more fuel to overcome that drag, resulting in reduced fuel efficiency.

In contrast, driving at lower speeds often allows for better fuel economy as the engine operates more efficiently and there is less wind resistance. Additionally, maintaining windows down may slightly affect fuel efficiency but not as drastically as high-speed driving does. Proper tire pressure is crucial for efficient fuel consumption as well, as under-inflated tires increase rolling resistance, but maintaining tire pressure itself does not contribute to poor mileage.

Understanding these factors helps in making informed driving choices to optimize fuel economy.