It sure would be nice if people would put the city and state of where they live. NO everyone is coming to visit you and try to steal your coveted ride!! ( Trust me I've seen yours ) This way if you live in a mountainous area, that could be why we are seeing low mpg. We won't have to assume that your driving habits are horrendous! Just a thought. People post pics of their vehicle but no location. If you give your location and no pic, all we know is that you posted under "1999 GMC Yukon" we won't be able to find you!
Thanks for letting me rant, Scott (ScooterAddict on motorcycle forums)
A few years back I drive my CVT first gen Insight from Williamsburg Va. to Blacksburg Va. then to just west of DC and back to Fredericksburg Va. before refilling. Lowest elevation was 75 feet (top of my driveway), highest was close to 4000 near Blacksburg. Hardly any flat ground on the whole trip, neutral coasting on some downhill parts at 85 MPH, just using the grade and got 70 MPG for close to 650 miles in one day and two hours the next morning.
Mountains can cost you MPG but they have to be more severe that I encountered. Driving with a constant load, losing a little speed climbing, with peak speed at the bottom of the hill can get you better mileage than flat ground, without nearly the peak high and low speeds. I actually chose my route to use the best hills for that technique.
I live in Williamsburg Va. Fairly flat going east, with rolling hills (Piedmont)
and mountain ranges about 2 hours west of Willaimsburg.
My location is listed in my profile but not on the forum, not sure why.