Did your MPG got reduced?Mine did and honestly very quickly, including having mort loud and shaky running engine to the point that even women noticed it.A every person who had a brand new car you going with your complaint to the dealer...., but dealer says that computer doesn't report any code = no issues. To try to learn what it may be the hidden cause you should understand how modern gas engines are built. They are built to be more efficient, but struggle to performing that way in long run and are not to built to last,.. only survive the 60K warranty.What I learn is that you can't have the engine oil in use for more than 5k. The carbon sludge and build up creates very quickly. So my first approach to solve the mpg was using additives into gasoline to clean the engine system..... it gasped a lot at first. Than the mpg went v up and down again, so I did engine oil flush, which jeweled tremendously. Car engine was immediately quite a it was at the day of purchase and mpg improved again. I was using the gasoline additives almost regularly as a precautions. At about 30k the mpg got very bad, almost 50% down. At this moment I considered to do tune-up, but first the simplest it seemed to try install new oxygen sensor even that car PC did not noticed anything wrong with it.The car has 11-13mpg driving in the city before changing the sensor. Nie it has 21-22mpg.I changed the oxygen sensor 1st time in my live and considering myself very handy and technically smart, I must say that it wasn't the worst thing to loosen it up with proper tools, but instead it was the wiring connector which gives some challenges (in my case). I had to remove cable brackets, connector bracket and cut out original zip-tie cables and then everything was easy and smooth work.Bottom line if your car mpg worsen a lot give this thing chance. I will still do a tune- up on my car as it hit already 40k. I insurgency few spark plugs (the way one to reach) and they already showing signs of being on the last leg.