As posted earlier, I recently replaced every gasket and seal on my engine (except rear main, and crucifix seals) as well as timing chain, oil pump, and did the Dorman fan and Hayden clutch upgrage. Two days later, I realised I had left my travel bag in my friend's daughter's car that I borrowed during the project.
So I filled the tank, drove the 90+ miles back to his shop to get my tote, and back home. The next morning, I filled my tank again. Based on my trip odometer, gallons added when I refilled, and using a difference in actual miles of .921 because I'm running 265/75/16 Duratracs instead of the factory size. I calculated my trip netted 16.7 mpg.
Not bad considering the original EPA mileage for a 2000 was 17mpg highway and I have 184k miles!!

 

True readings is to fill up and drive until empty.

 

I get 16 mpg everytime if it’s 90 % hwy

 

I get very similar frequently. 244k on mine.

 

You can remove another 3% or so from factor ODO reading fast as all cars do to avoid lawsuits and such. I remember the S2000 had a class action win because Honda worked TOO much fluff in, intentionally expiring warranties early. Fill up, GPS track it, fill up again, divide by mileage. Tire brand/model/size has a TON to do with outside diameter and a small change is a big change.

 

I recently drove 300 miles with a thermostat that was stuck open. The engine temp stayed around 160 the entire way. I did a mpg check expecting it to be bad but it came out to 16.7 which is right where it usually is.

 

I would be interested in what PSI you are running. When I jumped up from 28 PSI to 33 PSI I seen a significant increase in MPG

 

I am running 40psi in my load range E Duratracs

 

To this point - I turned on my MPG reading on the Ultragauge just for kicks and wasnt really paying much attention to it.
When I did, I was surprised. My D2 with factory size tires was 4-5 mph slower than the ODO said.
I turned on WAZE at that point and have run it side by side with the ultragauge and they're aligned - confirming my disco is 4-5mph slower than the ODO at all speeds.

On the other hand - my wifes 2003 Volvo XC70 is exact at all speeds, so i wouldnt go so far as to say all cars fudge this.
I've run WAZE quite a bit and always noticed the speed was the same as the odo until the Disco....
With that said, I avg about 15.5 all of the time, but my commute is 25 miles of mostly highway.

PS - I've tested higher PSI and all I noticed was a terrible ride - it wasn't worth any decimal point of mpg I might have gotten.....

 

I'm in the upper 16's lower 17's with oversized tires most of the time doing the simple math of miles driven to gallons pumped in.. I drive almost 70 miles a day, 5 days a week, so all hwy.



I do see better mileage with Shell gas vs. Costco which are basically the only 2 gases i get.