Why is my fuel economy worse even though I drive the same?

[ScottPL]

I’m trying to figure out if my car’s fuel consumption is normal or if something’s starting to wear out. My usual weekly fill-up is costing me noticeably more for the same commute, and I can’t pin it on any change in my driving or the gas prices lately.

[Aurora_T]

I had a similar thing last winter and my weekly fill up started costing more for no obvious reason. I started with simple checks and kept notes. The car seemed fine but the numbers stayed higher.

[Emma94]

Often it is small things you overlook like a clogged air filter or a sensor that drifts. You do not always get a warning light though.

[CharlesGH]

One time I drifted and started keeping a notebook for a few weeks to track fuel economy and a few odd things like cold starts and highway miles. It did not fix the issue but it helped me stay calmer.

[Jonathan.T]

Have you noticed a check engine light or rough idle that would point to a sensor or ignition issue?