2.7L MPG

^

They are independent, my odometer is off by 2% but the speedo more like 6%.

 

I can't answer the question why the speedometer and odometer do not exactly match each other. You can use the same test to find out which is giving you the right information....the gps or the speedometer. Go back to your know distance course. Set your cruise at 60mph using the speedometer and then set your cruise at 60mph using the gps. Which ever one says it takes 60 seconds per mile is correct. My money is on the gps.

zdog

 

I worked for the road department in Wa. for years. The standard for mile markers was set at plus or minus 300' for accuracy quite a few years ago. I worked with one guy who said he put out some of the original ones on some of our state highways. He said sometimes he would forget what he was doing, then just stop and put one in rather than go back and start over at the beginning. When mile markers are put in now they use Digital Metering Instruments but they are still put in by a person who may or may not care how accurate they are and there is error in the DMI's if they aren't set up right and calibrated often and the calibration is only as good as the guy doing it and the course it's set with, cold or warm tires, careful starts and stops and probably more. If the road has a lot of corners the radius' can throw off the millage because they are not usually driving down the center of the road, but in one lane and so farther in or out on the curve. So it would be most accurate to be in the lane the person measuring the mileage was in, or on a straight stretch. Also errant vehicle sometimes wipe out a marker and the person putting it back up may not get it back in the same place it was. And the next marker may fall in an intersection where it is impossible to put one in in the correct spot or it may fall in an asphalt parking lot, on a bridge, someones driveway, etc. We used to set up jobs using mile markers all the time and for the most part they are fairly accurate. To be off a hundred feet is common, two hundred is not unusual and sometimes they are three hundred or more. I have tried a couple different spots around here and came out different on one than the other. If the road has a lot of corners you will also come out different one direction than the other unless you have the same number and radius' curve going both directions. There used to be speedometer check sections in this state that were put in by surveyors that I thought was pretty cool, but I don't see them anymore. I think a hundred miles or more on the same highway, going in the direction of increasing miles would be the most accurate.

Just my two cents worth. Got kind of long didn't it.

It's accurate though.

 

Very good point. Here in Oregon they for some reason don't have mile markers that I have noticed lately. When ever I have calibrated my system I have used the mileage check markers you sometimes see on the freeways.

zdog

 

Using the GPS in my iPhone and various apps, my speedometer shows I am going 2mph faster than I really am, but my odometer is pretty damn close.

 

I think it works like this:

Speedo reads driveshaft rotations.
ODO reads wheel revs per mile.

 

just fueled up, 23.47

 

For a 4WD regular cab I can report 24 MPG on flat desert roads at 65-70 MPH with stock 225 tires. I don't think it can be pushed much beyond that due to physics, except for a long downhill run. Lifts and bigger tires will invariably kill efficiency.

A good way to save fuel in city driving (on flat roads) is to coast into stop lights below 30 or 40 MPH, which also saves the clutch. Over decades, I can't recall more than one or two safety issues with keeping it out of gear in those situations.

 

I always thought that I could save gas by coasting too. The other day I found an article that said different. I forgot to save the location but I'm pretty sure it was an article in popular mechanics. It said that starting in 1990 (I think) that Toyota went to engines that shut off the fuel when your foot is off the gas pedal and the car is moving in gear. The person who wrote the article thought it was about the same for most other cars around the early 90's also. His point was you get better MPG when in gear and your foot is off the throttle than coasting.

It seams like I do a little better when in gear than coasting. That may be more my imagination than anything. When your engine is idling I doubt it using enough gas during coasting to be noticeable over the fuel being shut off, if in fact that is the case.

I get about 23 MPG. I tried coasting on a couple tanks and got about 22 MPG. That could be just the weather or the topping off of the tank or one of many things I suppose. Too close to call. On one tank of gas this year I got about 26.5 MPG on the interstate. I expected more, but that's not bad I guess.

I found that Napa Auto Parts sells Amsoil so I am changing to that tomorrow.

 

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I'd like to see that article, it may be true in some cases and maybe only with automatic transmissions, but my results obviously differ.

 

Just did my first fill-up (2011 4x4 5-speed reg cab). Had a little more than a quarter-tank left. 12.165 gallons at 318 miles.... 26.1 miles

 

I have to remember to save those articles I guess. They were talking about manual transmissions because I remember talk about the clutch. I will see if I can find it. I can't remember how I got there or exactly what I was looking for but I'll give it a try.

 

I found a different Popular Mechanics article than what I read before but the same idea. This one is a little hung up on safety, but for what it's worth here is the link. The second link has some same and some different results.

http://www.popularmechanics.com/cars/alternative-fuel/news/coasting-in-neutral-fuel-economy

Here is another link that will take you to a forum where people are discussing MPG. One guy (CNCMike / Blow away EPA estimates) talks about getting better MPG by coasting as you said and there is another about coasting on flatter ground as apposed to steep hills. Injectors on some cars shutting off at zero throttle and coming back on at low RPM, better MPG by changing your oil at 3000 mile, drafting, fuel caps, etc. Some interesting talks and opinions if your interested.

http://www.opentravelinfo.com/travel-guide/uncategorized/how-to-save-money-on-gas-29-tips.html

 

Yep, no facts will change this persons mind, and he didn't really do any tests to back his claim, just theoretical. Only in the fictitious theoretical land where ever time you coast in gear the momentum carries you as far as in neutral does this work. But most times I coast in gear it brakes way too fast and I must give it more gas to continue. Sure I'll coast in gear down hills when i'd be braking anyway but otherwise it's neutral.

 

just did a top off. 6.85gal. 157mi. - 22.9mpg. all short driving. started at 17.5 mpg (2,027 mi. and winter). now getting to where it should be.

 

All I know is that the OBD ultragauge favors coasting. Just for example going down a hill in gear the instant mpg may show 80, push in the clutch and it jumps up to 120mpg. Thats my observation.

 

Just did two half-tanks, one at 20.7mpg and one at 21.1, by shifting at 2500rpm, cruising at 65 on the highway, and not running AC.

Edit: Look at my mods before telling me I didn't do good!

 

Unfortunately the author is correct on scangauge and ultragauge not getting it right during engine braking in gear. It should be infinite mpg while it shows 80 for you. Yet that's the situation I agree is good to keep it in gear if you have to brake anyway. The "gauges" don't actually measure fuel use, they calculate it and overall pretty accurately, just not during deceleration fuel cut off. They can only use the available information and approximate from there. Why they haven't programmed it so it concludes that during open loop and closed throttle fuel use is zero is a glaring omission, should be easy enough to do that.

On level ground or moderate inclines where engine braking will slow you down, coast it in neutral.

 

OK, I hadn't read the PM article--and still not sure I understand all the engineering details. But willing to give it a try: leave it in gear as long as engine breaking doesn't cause you to have to accelarate unnecessarily. I noticed my truck really rolls easy in neutral and picks up speed on the the slightest incline.

 

I noticed about a 1/2 mile loss in mpg when I leveled the truck (w/ Bilsteins). Kinda sucks... but does look better. Maybe I am just driving faster now though. It is hot as Hades here in Phoenix right now though (and has been since I leveled it)...that could have something to do with it too I suppose.