I hope the fit works out well for her.
I'm sure you are already aware but most oem on board computers are optimistic in their readings. The Elantra's readout is typically ~2 mpg higher than the actual calculations for my fill ups.
The decreased avg speeds that the EPA runs its testing at will not compare well to real world driving (people doing 70+ on the highway). This fact means for most people the numbers won't match. You car exceeding the EPA's numbers is not unheard of, Honda may also be conservative with its EPA numbers. For example, if you look at Pale's speed vs mpg chart for his Honda fit.
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