Hi all,

My 2017 IS200T at this point it is at 8500 miles and mechanically has been great, even though I have the worst, most rattling interior. It has always gotten 26-27 MPG since the day I bought the thing back in May. ...However, after I went to get gas 5 weeks ago, it was averaging 25.1 MPG (calculated manually and by dashboard fuel economy reader). I figured it was just an outlier, but the next tank of gas came and went and that one averaged 23.9 MPG.

I filled up again Monday morning right next to my house, and 3 days in and I am getting 24.1 MPG after 86 miles.

My driving habit is the same every day. I drive the exact same roads and highway every day: 4 miles of city roads (~10 minutes) and 9.2 miles of highway (~9 minutes) to and from work. No trips out of the ordinary or off that route, and everything is the same. Its funny, but my mileage is so precise that I actually have the gas light come on like clockwork every other morning when I turn it on to go to work...fortunately, I live beside a gas station.

I checked the oil and its good. Wheels move freely without any resistance when I jacked it up. My driving habits haven't changed. Without looking at the spark plugs or potentially an O2 sensor, I am not sure. This is just one more issue in about a dozen others I have had with this car that have required the dealer to look at it, but the first potential mechanical issue.

Any help from you guys would be appreciated!

 

Honestly it could be fuel related. I know increased ethanol in fuels can cause a drop in economy so can the blends that change in the seasons. A 1-2 MPG drop could easily be due to either.

I do mostly city driving and mine fluctuate between 18-20MPG.

 

 

low tire pressure, low tread, dirty air filter, sport mode?