[SentraSE-R]

I see you've got a Scangauge installed, and it's an automatic. If she can get it into top gear TC lockup early and just cruise at 60 all the way on the freeway, she should be somewhere between the mid-30s and low 40s mpg. Watch the rpms on acceleration, trying to keep them below the shift/TC slip rpm shift to 2500 rpm. Every time it kicks down, your mpg tanks. City stop & go is where you get your worst mpg, so coasting through lights and coasting well in advance of stop signs will gain her a lot of mpg. The other big killer is high speeds. The closer she can stay to the 55-60 mph range, the higher her trip mpg will be. It's very significant. Try a 5 or 10 mile drive on the same route at 55 and again at 70 mph. You'll see a 10 mpg difference between the two.