The harder you drive your car the less gas mileage you get for instance...When I drive at normal speeds for an average person i can get about 350 to 400 miles every fill up which is like 10 days or so with out filling up but when I drive like a bat out of hell like I usually do i get around 25 mpg which rounds out to about 250 to 275 miles evey fill up and that is like every 5 to 6 days fo rme or less....So pretty muc the harder you drive the more gas you burn which leads to decrease in mpg........

Hoped I helped!!!