Low City/Good Highway Mileage

My 2004 Chrysler 300M with 120,000 miles gets 12-15 city mpg, but 24-26 highway mpg. The oxygen sensor was changed 1 year ago, which minimally boosted city mpg. What might be the cause of and solution for such a radical mileage difference in my Chrysler 300M ? My previous 1997 Chrylser LHS with presumably the same engine got 17-18 city mpg.

Thanks - Peter

That car is EPA rated at 16 city and 25 highway. You’re getting the rated mileage.

The cause of such radical change is seven years worth of design changes and the fact that these are different vehicles entirely.

my 2000 300m gets 19-21 new jersey local roads and 24-27 on long trips. they are both 3.5l but they are different. ps did you change the timing belt. the “M” has more horsepower.