For a porch light I'd go LED, for interior I would not. Google light spectrum issues from LED and CFL bulbs for some interesting reads. You aren't getting the full spectrum of colors from them. So yeah, outside at night works for me, inside, (at least for me) I'm staying with old school.
4 whopping cylinders on Toyota RV's. Talk about great getting good MPG. Also I have a very light foot on the pedal. I followed some MPG advice on
Livingpress.com and I now get 22 MPG! Not bad for a home on wheels.