The duration a vehicle's gas will last depends on several factors, including fuel efficiency, driving habits, and vehicle weight. On average, a car with a fuel efficiency of 30 miles per gallon (mpg) will last approximately 12 hours on a full tank, assuming a driving speed of 50 mph and no significant traffic delays. This calculation is based on the assumption that a standard gas tank holds about 14 gallons of fuel.

The reason for this duration is rooted in the fuel efficiency of the vehicle. Fuel efficiency is a measure of how many miles a vehicle can travel on a single gallon of fuel. A higher mpg rating means the vehicle can travel further on the same amount of fuel. For instance, a car with a 30 mpg rating can travel 30 miles on one gallon of gas. Therefore, with a full tank of 14 gallons, the car can travel 420 miles before needing to refuel.

Driving habits also play a significant role in determining how long the gas will last. Aggressive driving, such as rapid acceleration and hard braking, can decrease fuel efficiency. According to the U.S. Department of Energy, aggressive driving can reduce fuel efficiency by up to 33%. Additionally, carrying unnecessary weight in the vehicle can also decrease fuel efficiency. For example, an extra 100 pounds in the car can reduce fuel efficiency by 1-2 mpg.

Data from the U.S. Environmental Protection Agency (EPA) provides further insight into fuel efficiency. The EPA's fuel economy estimates are based on a standardized test that simulates real-world driving conditions. These estimates can vary slightly depending on the specific vehicle model and year. For instance, the 2021 Toyota Corolla has an estimated fuel efficiency of 35 mpg combined (city/highway), which would mean the car could travel approximately 14.7 hours on a full tank of 14 gallons, assuming the same driving conditions mentioned earlier.

In conclusion, the duration a vehicle's gas will last is primarily determined by its fuel efficiency and driving habits. By maintaining a steady driving speed, avoiding aggressive driving, and keeping the vehicle's weight to a minimum, drivers can maximize their fuel efficiency and extend the time between refueling.