The Fiesta ST is likely one of the most efficient sports cars available on the market. This car has the potential to reach up to 40.0 mpg but you would have to be insane to drive this car that slowly. The car begs to be pushed through each corner making the real world mpg closer to 30, high 20s if being pushed to perform.
In my personal experience the fiesta ST has been sitting around 30 mpg since my purchase. I only reset the timer after my initial road trip and since then it has not changed significantly. I rarely put the car in 6th gear, even when cruising i prefer to have the power readily available, and I am constantly pushing the engine to its limit. Truthfully the mpg this car offers is simply an added bonus as i made this purchase for the performance, not for the savings.