I'll be picking up a 2006 GXP later this week.

What MPG can I expect with the D.O.D. V8 if I don't have an overly heavy foot?

In-Town?
Highway?
Combined?

The only modification currently is a K&N Air Filter.

Your responses would be appreciated.
Thanks in advance.

O.K....Apparently not too many GXP owners care about mileage (or, perhaps there are just not many members of this forum).

How about water infiltration in the roof? After the last rain I thought that I heard what sounded like water sloshing in the roof cavity in front of the sun roof. After making a sharp turn or two the sound went away or the water must have drained away. Should this concern me?

Well, I just got my car, and on the first tank I averaged 18.5 hand calc, 19.5 on the DIC. I am hoping to average more than 20 but now that we are on winter gas, I am not sure if that will happen. We will see.

I've had my 2007 since August, and am averaging 15.5 to 16.9 L/100kms, but that is with some heavy foot driving, and mostly in town (avg speed on the DIC is only 32km.h, Highway driving the car does MUCH better

Hard to keep a light foot with this car. Plus we are on the winter blend for gas now so that will knock it down a few mpg.

I have had my '08 since August of 2009 and I have a lifetime average of 20 mpg. I do alot of highway driving.