I've had my share of negative remarks while living in Massachusetts. Most were like "Why drive something so big?" or "EARTHKILLER!". I did have one death threat, and I have to say it was very funny. Also, I had one scary experience where a bunch of college aged guys (my age, but rowdier) approached the car late at night in a parking lot. They were shouting something, but I floored it out of there before I figured out what they wanted!
As for the 15 MPG, it is possible. First, reset the AVG ECON. Then, drive about 45-60 MPH on a highway with a light foot. This will probably get the display up to 15 MPG.
HOWEVER!, I had about 13 MPG showing on a trip the other day at 75MPH, and when I actually calculated the MPG from milage and gallons put in the tank, I ended up with about 15.2 MPG. So, the AVG ECON may not always be correct.
Yeah, as for the "some people have a death wish" comment, I agree. I've had that happen way too often. I pity da foo' who messes wit da Humma! as Mr. T might say.