I have had my new truck for about 4 weeks now. I just put in the 4th full tank of gas last night. I let it get pretty much bone dry before I filled up so I could check out the MPG. I have a little over 800 miles on the truck now and I bought it with 20 in rubber and duals with a flowmaster muffler. Im only getting a little over 11 mpg so far. I drive it approximately 20 miles a day back and forth to work on I-35, with the cruise set, and A/C running on low. I took it to the dealership this morning to make sure nothing was wrong with it. Perhaps the computer needs to be tuned a bit to compensate for the bigger tires, etc. Tech told me nothing is wrong with the truck and I should expect to see a gain in MPG over the next few weeks as the motor continues to break in. That sounded reasonable, but I wanted to get an opinion from you guys on that. Also, this thing downshifts on the smallest hill and down shifted a hell of a lot on I-44 from OKC to Lawton. The 03 STX that I had before had the same motor and NEVER downshifted as much as this thing does. I understand that its somewhat heavier than the 03 that I had, but I dont think that would make that big of a difference. Bottom line is, I am getting worse power and gas mileage than the same regular cab truck I had in the 03 STX. Only difference being that the 03 had smaller rubber (maybe 3 in smaller) and was probably a bit lighter.

I also wanted to ask about a good air kit and maybe any other small mods I could do to beef up the truck a little bit, power wise. Thanks for the input!

 

It's those 20in tires. With 20's your rear end is effectively geared higher(Numeric lower). It's probably keeping your engine just out of it's powerband. Stock rubber or lower rear end gears will solve this.

 

OK. Is this something that I can get the dealer to do at no charge, since they put the 20's on there?

 

Dealer put them on there? Hmmm. I don't know how they would work that issue. That would be a good place to start though. Give them a call and tell them what's up. Or if you like the 20's on there, gear down the rear end a little. Or, sell the 20's(they are probably worth quite a bit) and get some nice 17's or 16's with that money.......

 

Ya, I would kind of like to keep the 20's. It was one of the selling points of the truck. I dont see them lowering the gears for me though, that means work they dont get paid for. I guess if I was smart enough I could have had them do that as part of the deal.

 

I had the same conversation with someone at a gas station on the way to the track with my Mustang. Gotta pay to play. There is a tradeoff. If you want mileage, lose the bling. If you can afford 20's, you can afford the gas. At least that's what I always hear...

"You can's have everything, where would you put it?"
-Steven Wright

Put in some gears to keep it in the powerband. Unfortunately, you have the 4.6L- I feel your pain. I have the same engine, and with the stock 17's it downshifts on medium hills. I can't imagine the truck sitting on 20's. Ugh!

I don't know why it always seems like Ford is putting motors in all of their vehicles that are "just enough" engine for flat road driving. You hit hills, and they are anemic. The only real highlight is the 302's in some vehicles. Too bad they are always a gift from Ford, while GM and Chrysler as a whole seem to put adequate and almost excessive HP in their vehicles while getting better mileage doing it. I can't figure it out.

Good luck!

 

I can live with the HP and the low MPG. I can afford the gas just fine. I just wanted to make sure nothing was wrong. I had an 03 STX with a 4.6 and 17's and it never downshifted. I didnt think that 20's would make that big of a difference. Now I know, and knowing is half the battle.

 

You say it has 20" wheels but what size tires? the wheels are bigger and heavier but depending on the tire size your gear ratio may be the same as if you had the 17" wheels. The overall diameter of the tire is what changes your gear ratio.
You say the tire and rims were dealer installed so I would bet they went down on the tire ratio(profile series 70,60,55,etc.) to keep everything the same on the truck to prevent someone from complaining about the same issue you are having.
There have been tons of threads here about mileage with these trucks and unfortunately the reality is thay they love gas!!! Every ford I have ever owned (car or truck) has gotten crappy gas mileage. except for my 98 escort, 38+ mpg.
I have a friend that has a 4.6l screw with 33's and he claims he gets around 17-18 mpg. I'm sorry I just don't believe that.

 

your MPG may get better after a couple thousand miles. mine did. I put twenties on mine with a 34" tire and it did not effect my MPG. Your truck looks very good keep the 20's.

 

try this link to see the acutal tire size difference.

http://www.miata.net/garage/tirecalc.html

This calulator should give you the difference in size from stock to the 20's

Lance