It most definitely will, but the exact boost in fuel efficiency will depend on the actual kit. On average, you can expect an extra 2-3MPG. The most advanced (and expensive) cold intake systems can even improve the mileage by up to 5MPG. In the long run, that can save you a lot of money (like 150-300 US dollars a year) and compensate for the steep price-tag. Your Jeep’s make, model year, engine, and fuel will also affect the efficiency, by the way.