Final answer:
Regular maintenance is the best option to improve your car's gas mileage. Speeding, frequent acceleration and braking, and carrying unnecessary weight can actually decrease gas mileage.
Step-by-step explanation:
The correct answer is c) Regular maintenance. Regular maintenance can help improve a car's gas mileage by ensuring that the engine is running efficiently and all components are in good working order. This can include tasks such as changing the oil, replacing air filters, and keeping tires properly inflated.
Speeding (option a) can actually decrease gas mileage as it requires more fuel to maintain higher speeds. Frequent acceleration and braking (option b) also reduces gas mileage, as it increases the energy needed to accelerate and wastes energy in braking.
Carrying unnecessary weight (option d) can have a small impact on gas mileage. The extra weight increases the load on the engine and can result in increased fuel consumption.