While K&N air filters have benefits of excellent filtration and air flow while being backed with a 1,000,000 mile warranty, K&N performs extensive testing on all of our products before they are released. These tests ensure that our filters provide sufficient capacity and efficiency, and provide an increase in vehicle horsepower. We do not claim that fuel economy is guaranteed to increase.
The U.S. Department of Energy has issued a list of recommended maintenance items which can improve your vehicle’s fuel economy. This list can be found at http://www.fueleconomy.gov/feg/maintain.shtml.
One of these recommendations is to periodically check your vehicle’s air filter. Replacing a dirty, clogged air filter with a clean, free-flowing filter can significantly improve your vehicle’s fuel economy, according to the US Department of Energy.
Fuel economy is a factor which is very hard to estimate. K&N does not have the equipment or facilities to test for possible changes in fuel economy. The vehicles used in our testing procedures are loaned to us by customers local to our R&D facility. Typically, test vehicles are kept for 4-5 days at the most. A thorough fuel economy test can take weeks to complete, and variables such as vehicle load, driving conditions (uphill, downhill, wind, etc.) temperature, grade of fuel, and vehicle modifications are difficult to factor in. Over time however, one generalization has proven to be true: customers with more aggressive driving habits typically see mileage decrease, while customers with more conservative driving habits often see mileage improve slightly.
K&N Product Specialist