Poor Gas Mileage. Thoughts as to why?

Bought the '14 MDX in Nov with a big plus being the increased fuel efficiency over the '13s still on the lot. My wife is the primary driver and her 20mile commute is 90% highway. Admittedly she has a pretty heavy foot and isn't great about warming the engine up. We have also had our share of cold weather in this New England winter. All reasons for less than ideal mpg. I started tracking her mpg and have averaged 17mpg over three tanks. I am seeing that some of you are getting ~30mpg.

I am wondering if I should go check some high demand setting that may be engaged? We aren't towing anything and we don't have a roof rack.

Thoughts? Wait until spring and then worry about it?

Thanks.