I live in Florida where everyone drives 75mph on the highway.
My friends, who have Honda CR-Vs, Nissan Rogues, and Foresters, all get within a couple of miles of their EPA highway mileage ratings when driving at this speed (the CRV exceeds it's rating!).
My 2016 CX5 Grand Touring, which now has 23000 miles on it, has consistently only gotten 28.0 mpg when driving at this normal highway speed (20% below the EPA rating). I follow all the "tips" to improve mileage.
When I complained to the dealer (after 5000 miles) they said it would probably improve with time. This never happened.

I'd never buy another Mazda without first testing the mileage for myself on the highway.

 

I'm assuming your measurement is by filling the tank or are you going off of the digital readout? Try holding a steady 70mph and resetting the "avg mpg". Tell us what you get after 10 miles on tha avg. readout. Above 75mph you will drop to 28 or so but at 65-70mph I routinely get 30-32mpg. For an SUV these are good numbers but speed is a major factor for any vehicle. Also, go to Fuelly.com to compare numbers and get tips.
I use an oil additive and the K&N air filter that both help me a wee bit. Just trying to determine if it's the car or not.

 

Please understand it is not physically possible for a K&N (or any other low restriction filter, or even no filter at all) to improve fuel economy. Why? Because modern fuel injected cars weigh the intake charge downstream of both the filter and the throttle body, as such, the proper air to fuel ratio will always be kept intact, regardless of how much or how little intake restriction exists upstream.

 

What you say may be true, however I'm saying if my avg economy was 28 and goes up to 29, that's a "wee bit". It may or may not be because of the filter but it still went up. Do not do add the K&N filter for the purpose of fuel savings! See my accessory thread for the real advantages of the K&N filter.
Same with the oil additive. I see small gains with and see small loss without.

 

Like I wrote before, there is literally a 0% chance a K&N filter will improve fuel economy; if you noticed a bump it was due to a different factor.

Lots of folks believe there are advantages of K&N filters, in the real world there are nothing but negatives. When I'm looking at used cars, if I see a K&N on it, I shut the hood and walk away, this regardless of how good a deal the rest of the car may be.

 

Check date of original post. Just did trip going 75-80 highway from MD to PA to NJ. 28 mpg for tank. But have 2013 FWD w 2.0 engine, not the heavier AWD Grand Touring w 2.5

 

I don't understand your dislike of the product but I've had several of their filters over the past 20 years for various cars and never had a failure and they are reusable. What type of problem did you have with them? Just finished 2 round trips of over 250 miles with avg speeds of 70mph. Tank avg (manually calculated) was 31 and 33 mpg for my GT-AWD.

Getting back to Suzie's original problem... Did you try resetting the "avg MPG" readout while on the hwy?

 

The problem with low restriction air filters is they let a significant amount of dirt into the engine, and contrary to the popular misconception they save money, they don't. So, no improvement in fuel economy, no improvement in performance, and a significant reduction in filtering. What's to like?

 

Assuming you're right, they pass lots of dirt and don't improve economy, I've not have any engine trouble, logging over 600,000 miles in the past 17 years. Assuming a new air filter every 10,000 miles (@$15 ea.) I've saved an estimated $900 minus the price of 3 K&N filters (@ $50 ea) nets me a savings of $750.00. I'd say that's a significant advantage. If you're green it also kept 60 old filters out of the landfill. What's the problem if I've not had a problem? How about starting a new thread on "best air filters' so this fellow user can get his/her problem answered.

 

Why on earth would someone replace an air filter every 10,000 miles? Absolute waste of money. I typically go between 50,000 and 75,000 miles on an air filter; depending upon conditions.