I just got my 4 wheel camper, a Hawk on a 2004 Silverado extended cab with short bed. I had a fiberglass topper before that didn't go above the cab. The previous owner swore he got 21 with the topper. I never got over 19, usually averaging 18.5 or so. I knew he drove more gently that I did so I didn't worry about it. When I got the 4 Wheel Camper I went north about 500 miles to Colorado east of Denver. I had the tailgate off and nothing in the back and got about 17. I was climbing mountains but that's normal around here. I got the camper and filled the tank, then headed up an extreme 4x4 road for the night. In the morning I filled the tank again and for that 120 miles took 10 gallons of gas. This was for really slow, 4low operation, picking my way up a mountain at night. On the way home I encountered much of the same amount of up and down highway that I had on my way north. When I filled the tank, I was shocked to find that my mpg was 20.63. I even tried putting more in the tank, but only got less than .1 gallon more. I couldn't believe that I was getting better mileage with the 4 wheel camper at 700 pounds and no aerodynamic attempts at all than I got with my 150 pound fiberglass topper with very good aerodynamic design.
After a few days my wife and I loaded it up for a camping trip and went to look for colored leaves. We again got more than 20 mpg. This is a lot less than my motorhome towing a samurai (1986 Vixen 21D -25mpg) but we bought the 4 wheel unit for a trip to Alaska next year and close by back road trips in NM, CO, AZ, & UT that we wouldn't want to take the Vixen on. We really like the simplicity of the 4 wheel and the roads we have taken it on so far were very spectacular. I am really also impressed with my Silverado. I owned several Ford F150 while working since they were the most dependable units and a couple Jeep Comanchees and one Dodge Dakota. All of which were fine trucks, but always stayed clear of Chevy. I got it mainly because it fit my profile better. It is great. My brother in law and a good friend of mine own Toyotas and I recently had to drive one because that was what the Toyota dealer gave me when he needed to keep my Prius for extensive work, and all I can say is that if you own a Toyota and love it, you must not have driven anything else. All of them take a real man to keep them on the road. You are a real man. I find myself weaving all over the place it I try to go above 60mph. My brother-in-law was driving behind me on interstate 75 in Georgia and had to call me to ask me to slow down so he could catch up. I thought something was wrong with his truck when we traded vehicles, but after driving others, found it was normal for Toyota.
Back to the subject, I don't know what is up with my truck, it is not normal, but I don't want to change anything. I tend to be a bit of a lead foot and always drive a little over the posted limit, which is 75 in my state on the interstates, so don't think I am babying it. I have talked with other owners and am afraid to have any work done on it. I have a laptop program that give me full access to the computer, and I will interrogate it and try to figure out why.
The only problem this truck has is that when I get gas, the engine will stumble some for about 20-30 minutes. Not bad, but annoying. I suspect water in the tank, and keep intending to put in some drygas additive but haven't gotten around to it yet.
By the way, for those who might thing the speedo is wrong, it agrees with my GPS.
) I still don't drive much faster than 70.
