Gas mileage decreased

I don’t miss them days.

I’m getting about 19 in the summer and 17 in the winter.

 

I get in the low 20's on highway trips. Around town mostly S4 I get 16 mpg on dash guage.
So have you cleaned your MAS? How about new PCV ? Are tires same? What tire pressure do you keep in your tires ?Air leaks and tires usually need more air after 3/4 months. Low pressure increases rolling friction and makes lower MPG.
Best way to get actual MPG is to fill tank with gas, record gallons and distance traveled from odometer. After about 4 tanks calculate your total MPG.

 

Disconnect battery terminals from battery and touch them together for 30 seconds.... reconnect to battery.