gas mileage issue city and hwy same

I wanted to post this question in the general and a more specific forum because the answer may be a general issue that is not necessarily specific to my 06 Max SL.

My car gets pretty much the same gas mileage around town as on the hwy. It does not vary much. Around 20.

So, my question to you mechanical gurus is "what sensor or parts may be failing to cause the car to meter the fuel/air (or whatever) properly for hwy driving?"


Thanks.