If you wanted to run an ANOVA to test whether the gas mileage was better in a Honda Accord, a Toyota Corolla, or a Hyundai Sonata, the null hypothesis would be

that the gas mileage is not the same for all three cars

that the gas mileage is better for at least one of the cars

that the gas mileage is different for all three cars

that the gas mileage is the same for all three cars