I think why the MPGs aren't in the twentys is because maybe some of us use the gas pedal with a lead foot . At least I do. Remember that old TV commercial where the pitchman put an egg between his foot and the accelerator pedal? They were trying to say easy on the gas pedal . Plus you start messing with big tires, ratios and other modifications and bingo; another pit stop to the ole service station . I used to get around 20+ , but now...............

 

okay, so there are those who are doing 20+ in the I6 :-)

 

I have always got about 12 MPG with my I-6. I drive like an old man, because I am. Don't give me that crap about an egg. My six has always got poor MPG. I have had the truck since it was new in 1979. I got it off the dealer with a 3 speed stick, not even a radio, NOTHING to affect the MPG. So you guys that get in the 20's must be smoking something other than tires.

 

Sorry but I don't smoke anything, maybe the tires when I want to show off a little, but that is about it.

 

I'm runnint 2000 rpm at 60 mph with a 5speed, 3.08 and 255/60/15's.

One thing that hasen't been mentioned as an influence on mileage is speedometer accuracy. Manufacturers are currently allowed a 4% window for accuracy. How many trucks are out there still running on the original everything? If the speedometer is off 10%, the calculated mileage could be off by even more because the truck could also be going 10% slower than indicated. For example, if your speedo says you are going 60 mph, but you are really only going 54, you will be using less gass because you are going slower. At the same time, the odometer is throwing the miles up there 10 % faster than it should. Two 10% errors can add up to a total error of about 22%.

 

I also thought about that, and so I used the road signs and mile markers to know how far I have gone.

 

I just registered my first I6 last week. Haven't accurately figured it out yet but I did check the miles traveled on the front tank. I went 214 miles before stopping today to fill up with an 1/8th of a tank still left. This is an original, 1993, fuel injected, 65,000 mi., 5 sp., 4x4 F-150 P/U truck. I will accurately check over the next couple of months and let you know.

 

23.1 once on a trip to camp a few hours driving during the weekend around the mountian and back home 2 hours highway on Sunday. The truck was bone stock. 94 f150 reg cab long bed 300-6 5-speed 3.08:1 4x4. uncovered bed factory 235-75-15 station wagon type tires. Now it's lifted 6" running on 35's with 4.11:1 gears. I'm afraid to check, but I love it.

 

When I changed the rear end ratio and went to taller tires, I went to my ford dealer and bought different speedo driven gears. Then I sat down with a calc. and crunched the numbers to see what driven gear I needed. Put in the correct gear and did mile marker test. Right on the button. And I didn't even smoke anything. And I always make sure the emergency brake is off when I drive.

 

It also has a lot to do with the speed we're driving.

I believe someone on this forum posted a link to a graph that displayed average gas mileage at certain speeds. It was mainly based on wind resistance. 55mph was about the best, and the mileage started dropping rapidly on the graph at greater speeds. Granted the Y-range was probably only 4mpg but there was still a substantial difference.

I like to travel at about 70-75mph. I seem to get the best smoothness and speed at that rate. Any faster and the fact i'm driving a pickup is made pretty obvious, any slower and i get anxious.

Best mileage that i calculated was 16.1mpg. It put a huge smile on my face. I've gotten 10mpg around town, driving like a teenager.

 

i usually get between 10 and 16 depending on the time of year and how heavy my boot was that week.

 

My best (23) was due to the fact that I drove 55 MPH with a fiberglass top and a steady foot. But that was just once.

 

I get 15-17mpg
bug things, 3.55 gears, maz 5 speed , stock tires, 3in body lift,
removed 2ed cat and piped with a flowmaster 40 2 1/2 in and out.

99k miles on the motor and i do 50/50 highway city and my speed is around 55-63

 

I have a 92 4X4. I keep up on the tunes ups etc. I am getting 15+ (right now in the winter with this fuel). This is on a 50/50 mix of city and highway miles. With summer fuel I expect to get a bit better 16+. I am fighting a pull to the left right now on braking and more noticable in 4x4. I plan an alignment. IF that is a problem, I will probably improve a little too. This is all stock (to the best of my knowledge). I did notice that when the exhaust detached aft of the cat, I got substantially better milage.

 

You guys are talking about summer and winter fuel, what is the difference? I live in PA, does it affect me here?