2012 Pro-4X Sudden 3MPG drop!?
I've got a problem here that is driving me nuts and I hope you can help. First, let me note that I've searched the forums but not found an answer to my satisfaction, so I apologize in advance for another MPG related thread.
My wife and I bought a brand new Pro-4X with 200 miles on it on Sept. 1, 2012 as I wanted one of the last Nashville produced models before they moved production to Georgia (funnily enough, I also just moved to Nashville from Delware in January). I immediately installed a flat KN drop in filter and swapped the factory tires for Cooper ST MAXXs of the same size. These are my only mods as of yet.
Once we got it over the break in period (i.e., 2000 miles), I was hitting 16.5 in town, and 19.8(!) on the interstate at 70 mph with cruise on. I was a super happy camper.
We hit about 4,000 miles on the odometer around Halloween 2012, which was also when the temperature in Delaware dropped to cold as heck, and, I assumed, the winter gas blends kicked in. I also got my first oil change then.
In early November 2012, when I started using the heater for the first time, I noticed the sound of "drops" hitting the factory skid plate. The car had never had ANY leak of any kind before (that I could hear). I figured this was due to the compressor being on and generating some condensation. Regardless, the truck still emits some of these drops now, whether or not the heater is or has been on. I have looked underneath, and none of the drops appear to be anything other than water.
Also in early November 2012, I noticed a terrible drop in gas mileage. I went down to 16.5 on the interstate (70 mph with cruise on) and about 12.2 in town. I have not changed my driving habits, am not a lead foot, and generally am cognizant of my RPMs. In sum, I'm the guy who pays careful attention to my enginge performance and driving style.
Last, although I'm not sure because I've never owned an Xterra before, I think the truck started shifting too much/easily at city speeds (e.g., from start to about 40 mph) at some point close to the mileage drop. Compared to the 1996 Explorer I was previosuly driving, the Xterra seems to shift up and down WAY TOO MUCH on relatively flat city roads, especially around 30-40 mph.
Has anyone else experienced this weird drop in MPGs? I had read a lot of positive reviews on modern Xterra fuel efficiency, but am baffled and concerned by this development. I thought it could be winter gas, cold weather, underinflated tires (I'm always at 50 psi on the MaXXs), but surely none of these is the reason for my loss of 3MPG!
I know these trucks are gas guzzlers compared to hybrids, and I'm ok with that. However, the sudden loss of 3MPG for no reason worries me, and is too much of a drop for me to just let it go.
Besides, I want to get a Shrockworks front and rear bumper installed. These 3 MPGs were the ones I was saving to sacrifice to the Shrock!
Any and all suggestions are welcome!!
Son of a Gunsmith