I have a 2007 TCH with just a shade over 2,500 miles on it (I know, I dont drive it much. I have a 1997 Tacoma I use in my business and during winters here in Montana)
Last week on a trip from Kalispell MT. to Missoula MT. and back I used 6.3 gallons of fuel to travel 257.1 miles. This it up and down some pretty steep grades at legal highway speeds (mostly 75 mph.)
Tires @ 36psi (Michelin MXV 4's)
Mobile 1 0W20 synthetic oil
Didn't use the cruise at all
I'm happy with that mileage, I usually get around 38 to 39 mpg around town.

 

Lets say you gained 4 mpg combined by the switch to full synthetic 0W-20 oil. Almost 2 mpg of that would be the oil and the other 2 or so would be due to the warmer air. It's been in the mid 80's where I live and the mpg has really picked up if I can keep the AC turned off.

 

I get 47 mpg highway, most of the time. If we do lots of mountain driving, 45/46. In the flat areas I drive 65 miles per hour using the cruise and no air conditioner, when possible.

The reason my readings are higher is that I live in the high desert in southern New Mexico. The average elevation here in the desert is 4300 feet. The humidity here averages about 20% and at times down to 15% during the hot summer.

My highway routes are Alamogordo, NM to El Paso, Texas. The other is the highway across and in front of the White Sands Memorial Park and through the missel range.

I also do all the good stuff. Easy acceleration up to speed. I do the 40psi cold in the michelin energy tires. 0W-20 synthetic oil, I use the cruise even in town. I do pump down the cruise when climbing a hill, then pump up, back to speed on the downhill side. This gives me a few extra miles per gallon.

 

Are people talking about the MPG the car says you are getting or what you calculate yourself? My car says I get between 40 - 41 MPG however my calculations have never come out to more than 38.5. I am only on my 4th tank.

 

My last tank said I was at 42.3 and hand was 41.67. First time though in 9 fill ups.

 

My last tank said 40.9 but by hand was only 38.5. 2.4 MPG difference, I wonder why so much, is this normal?
CoolShock was less than 1 off.

 

First time for me too but in 12 fill ups. Last tank was 40.4 by hand. Only thing different is the weather is getting a bit warmer (hence not using the heater as much). Oil change to 0W20 1600 miles ago may be starting to help too.

I've lost faith in the TANK AVG reading on the MFD. When comparing it to hand calculations after a fill up it has varied by as little as 0.2 MPG and by as much as 4.3 MPG for me.

 

I have that same exact problem. The display shows about 2 to 3 mpg higher than what I calculate. I may start using my 1" boards and place them under the on the low side wheels on the passenger side. This might work better during a fill up. I notice my car always leans out from the pump and is not level. One night late I placed a long level down and it took a 1" board to make it level. I did the board thing for years with the '03 Corolla and the '06 Ford 500. I do remember getting some .3's and .5's difference in the readout vs the calculator.

My wife don't like placing the boards, but she does like this car being a fume burner compared to some the old carburated cars we had.

 

https://www.greenhybrid.com/discuss/...atabase-17513/

I have found mine to be off anywhere from .5mpg to 3 mpg. The link above is a little analysis I did on the database to see how much the database was skewed by people who only used the MFD to report their MPG info.

Personally I use the MFD as a guide and always calculate by hand. One thing to remember is that the hand calculations aren't 100% accurate either as you don't know if you always fill your tank up to the EXACT same point everytime.

 

Coolshock1,

When doing them by hand (I do) they may be off a little on any single tank but the overall average after several tanks will be correct. My average would increase by roughly 2 mpg if I took the MFD as being correct.