I,ve got 800 miles on the car and it gains MPG every time I drive by at least 6 tenths every trip on the lifetime average. I'm up to 38.5, and on short trips it seems to be getting around 42 in this cool weather. I would vote a yes at this point as it improves every trip. Its hilly here so its hard to get the same average on oppisite directions on my daily drive.