Should I trade in my 2008 Scoin XB for a 2007 Honda Civic fully loaded with options like nav?

I wanted to trade in my 2008 Scion Xb, which I absolutely love, for a civic because the XB isn't getting as good as gas mileage as I wanted (27mpg). My boyfriend has a 2007 Civic and I love that one too and they also get 36 or more mpg. However, I have 5years left on the scion to pay off and with a new plan with the civic it'll be 6 years instead of 5. Should I go for it and save the money on gas right now?