Does an induction kit or an air filter use up more petrol than normal or how much?

Answer 1

NO! In fact their infamous claim to fame is improved horsepower which translates into fuel savings if it takes you less ponies to achieve the same goals with speed and or torq. However, all these do is cool the incoming air and less air restriction between the fuel air intake system. Just remember. the more the air flows the more the smaller micron of debree gets through. That's why you never see the air hog or K&N filters on new cars.