Best MPG ever

BVCRD · **Posted:** Thu Jul 03, 2008 12:51 pm

I got 30 last week on a run into Denver and back, total of 275 miles.

Sir Sam · **Posted:** Thu Jul 03, 2008 1:20 pm

RTStabler51 wrote:

How are you guys figuring a 10% error on the speedo? According to my Garmin GPS the speedo is accurate.

Anyways, 14mpg worst (don't recall why)
Just over 30 as my best by far.

The speedometer and odometer seem to be independently incorrect.

Bill.Barg · **Posted:** Thu Jul 03, 2008 2:47 pm

Pablo wrote:

Bill.Barg wrote:

Pablo.... did you have your AC on for this 25 -27 mpg ?

Yep, On recirc. Fan on 3 or 4, temp most of the way to cold to all of the way to cold. While it does get cool, it never really gets "cold" of course, with it being 112+ on the road most days.

I take a big hit on mpg with the AC on 1.0 mpg typical.... the AC does not really make really cold air either!. I think there is some bad efficiency with the AC system.... not sure how to find out, however.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

Bill.Barg wrote:

Pablo wrote:

Bill.Barg wrote:

Pablo.... did you have your AC on for this 25 -27 mpg ?

Yep, On recirc. Fan on 3 or 4, temp most of the way to cold to all of the way to cold. While it does get cool, it never really gets "cold" of course, with it being 112+ on the road most days.

I take a big hit on mpg with the AC on 1.0 mpg typical.... the AC does not really make really cold air either!. I think there is some bad efficiency with the AC system.... not sure how to find out, however.

On mine it drops 1-2mpg. I suspect that is not too out of line. What I did not expect was that with the AC on the EGT takes much longer to drop than with it off.

Bill.Barg · **Posted:** Fri Jul 04, 2008 12:12 am

Pablo wrote:

On mine it drops 1-2mpg. I suspect that is not too out of line. What I did not expect was that with the AC on the EGT takes much longer to drop than with it off.

Ya... that AC EGT corelation is odd. Maybe it is that the ambient temperatures are so hot , thus the AC, and the turbo does not cool as fast ?!?
Maybe it is the fancy engine controls that keep the RPM constant when the AC is turned on, so you do not notice a 10% drop in available power all at once! So at idle, the engine has the same RPM but is burning 10% more fuel,,, hence the hotter EGT ?!?!

2 mpg drop for AC? Lets say 10% of the average engine power (80 hp) = 8 hp = 6000 watts !
That is 1.7 tons of refrigeration... .enough for a small house. And it barely works to cool a small truck!

Yikes

geordi · **Posted:** Fri Jul 04, 2008 11:29 am

That seems like an awful lot of drain on the engine. At idle, my CRD only burns .25 gallons per hour, with the AC on. I confirmed this reading from the SGII by filling up at night, then got about 8 hours of sleep at a truck stop. Filled up again the next morning - 2 gallons just about even.

With the AC off, the SGII reads that the car is using .18 gallons per hour. Thats not a huge drop, less than 10 percent of a gallon per hour of operation.

I'd question if something was wrong with your AC, but then again... It is the summer, and when I was on that trip a few weeks ago, I was towing and my AC wasn't making me frigid either.

When its 90+ out... Your AC isn't going to make the inside of your car 30.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

I am not too worried about the AC . It blows ice cold. When it is 112+ ambient, it is going to be 130-145 on the blacktop. I am impressed it cools down at all, that is alot of airspace to cool after it has been parked out in the hot sun all day (employer too cheap for covered parking). Now that I think about it, at these temps the hydraullic fans come on more to move air (It is almost always on in summer here). So it may not be the ac that is dropping the mileage as much as that beast of a fan in stop and go traffic, but I am not turning off the ac at 110+ to find out how much of a difference it makes!

BTW, had to haul butt to a meeting the next day and did 80mph for 50 miles. Filled up that night and got 25 mpg. So nothing special after all, but not bad either.

Threeweight · **Joined:** Mon May 14, 2007 5:57 pm **Posts:** 679

400 mile road trip, towing 2500# camper over the Oregon Coast Range and up and down Highway 101, with two kayaks on the roof, 2 people, dog, and 100 pounds of assorted gear, averaged 19.5 mpg. That's with B20, keeping the speed at 55 mph on the country roads and 101, 60 mph on the interstate (trailer aerodynamics gave the mpg a huge hit above 60). Pretty happy with those results.

Was kinda funny talking to the big Ram and F250-350 guys at the campground who were lamenting the price of diesel and comparing mpg. They were thrilled to get 14-15 mpg towing a trailer just slightly heavier than ours.

Best MPG ever

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