I bought this spark plug for 2019 Mazda CX5. I read several negative reviews that made me concerned. One reviewer indicated that the spark plug gaps were incorrect. I checked mine and all four were correct. Note that the spark plug for turbo version of Mazda's Skyactiv engine has a differerent gap than the non-turbo engine. I am wondering if some of the reviewers are misapplying the part. There was also a complaint about loss of fuel efficiency after replacing the spark plugs. That is serious becuse the engine is a direct-fuel-injection type and it is prone to carbon buildup if fuel is not fully combusted. I decided to collect my car's baseline mpg data before I replace the spark plugs and compare it to the mpg I will be getting after replacing the spark plugs. It turns out many things affect the mpg. I had to collect average mpg over a minimum of 40 mile trip to get a repeatable and reliable data. Ambient temperature and vehicle speed (mph) also affect the mpg. I collected mpg data on long trips from Dallas to Houston, Texas. The 1st was on Dec 24, which was before replacing the spark plugs. I started with a full gas tank; drove at posted speed limits for 261 miles; and when I arrived in Houston, it took 7.582 gallons of gasoline to fill the tank back to full. That resulted in 34 mpg. I replaced the spark plugs on Dec 31st and made another trip from Dallas to Houston on Jan 7th. This time, the trip consumed 8.497 gallons for a 262 miles trip which resulted in 31.5 mpg. That was a loss of 2.5 mpg with the new plugs. I knew that the ambient temperature was lower for the latest trip compared to my trip in December. I decided to repeat the test again. Today, Feb 4th, I made another trip from Dallas Houston. The ambient temperature was 61deg F when I left Dallas and it had dropped as low as 53 deg F at some point in the trip. It was back to 61 deg F when I arrived in Houston. This time, the trip consumed only 6.786 gallons to travel 265.3 miles; which equals to 39.1 mpg! I am wondering if temperature alone can explain the increased mpg for the latest trip or somewhat the spark plug needed some time to be broken-in before it performed well. I do not know the answer. My conclusion is that my new spark plugs are performing as well or beter than the old spark plugs. Will I buy these spark plugs from Amazon again? Probably not. Yes, the part performed well, but I still don't want take a risk of buying a counterfeit which could damage the engine, just to save something like $20 or $30. Next time, I will buy only from a Mazda dealership or from NGK authorized distributor. AutoZone, Advance Autoparts, O'Riley and NAPA are all authorized NGK spark plugs distributors.