Long commute vehicle?

valkraider · **Posted:** Thu Mar 09, 2006 1:14 am

Here we go again....

retmil46 · **Posted:** Thu Mar 09, 2006 1:43 am

oldnavy wrote:

Endurance wrote:

I would be a little careful with the gasmileage other users seem to get. In my CRD I am getting 20 mpg on Highway right now, my moms gasser got 21 mpg driving the exactly same trip at same speed. We'll see how my gasmileage develops, I only drove 1200 miles so far.

Daniel

For one are you sure you are doing the math correctly?

Also the CRD does not use gasoline and may be why you have such poor fuel mileage.

Well, at least you didn't tell him to pick up some chow line and relative bearing grease next time he's at the hardware store. :lol:

oldnavy · **Posted:** Thu Mar 09, 2006 4:18 am

Just noticed I left out the smiley faces, I was kidding the guy and after looking back it does look like I was trying to apnk him in public.

Most likely it's poor quality fuel, inexperience driving diesels, and just maybe measuring, all combined. :wink:

LibertyCRD · **Posted:** Thu Mar 09, 2006 8:34 am

Well I must say...not to offend anyone here... but when my CRD was bone stock I NEVER got 30 mpg out of it. The most I ever got was 26 mpg and that was driving on the highway 80% of the trip and driving in a way to maximize my mileage on purpose. If I drive it normally I'm seeing 23-24 in the summer. And this winter I have also been seeing 20 mpg...even on the highway. So this guy is not completely off his rocker. There are way more people getting low 20s than there are getting 30 out of these things. Just my 2 pennies...

oldnavy · **Posted:** Thu Mar 09, 2006 10:41 am

I'll bet it still has to do mostly with low cetane fuel. I run 49 cetane fuel which is what the engine was designed to run on. I bet if I switch to the regular 42 cetane crap sold by local BP or Citgo my MPG around in town, which is currently 22 mpg, would probably drop 20% to 18 mpg city and maybe down to 24 mpg highway or even lower if fuel were 38 to 40 cetane which is not that hard to find here iun the US.

irunmiles · **Posted:** Thu Mar 09, 2006 11:20 am

I have a long highway commute of 40 miles each way over flat roads, have 12,00 miles on the odometer, use the local truck stop diesel and add PowerSource centane boost with every tank, keep my rpms under 2000 - and still I only get 21-22 mpg. I'm also a professional engineer, so my math is correct.

bigcanoe · **Joined:** Mon Oct 31, 2005 5:33 pm **Posts:** 96

Serious question...are there any other vehicles that can tow 5000lbs that can get better MPG?

LibertyCRD · **Posted:** Thu Mar 09, 2006 11:47 am

bigcanoe wrote:

Serious question...are there any other vehicles that can tow 5000lbs that can get better MPG?

This is THE thing that makes the Jeep stand out from the crowd. Sure the hybrids might get just a tad better mileage..maybe. But can they navigate serious off-road trails, tow thousands of pounds, and get high 20s for mileage on the Interstate?? I don't think so.

The Jeep CRD is a vehicle that excels in EVERY category...and that makes it shine. Too bad none of the journalists understand that.

Endurance · **Posted:** Thu Mar 09, 2006 12:01 pm

LibertyCRD wrote:

Well I must say...not to offend anyone here... but when my CRD was bone stock I NEVER got 30 mpg out of it. The most I ever got was 26 mpg and that was driving on the highway 80% of the trip and driving in a way to maximize my mileage on purpose. If I drive it normally I'm seeing 23-24 in the summer. And this winter I have also been seeing 20 mpg...even on the highway. So this guy is not completely off his rocker. There are way more people getting low 20s than there are getting 30 out of these things. Just my 2 pennies...

Thats exactly what I think!

And NO oldnavy, Im not an idiot, I know how to calculate my gasmileage. :roll:

I think this thread should be moved to the Mileage Forum or whatever its called.
And I also think that people who say 30mpg is normal Highway gasmileage for a CRD should
check out 1 or 2 threads from that forum. I have the impression that 20-25 is much more realistic
than 30. Now I dont know what kind of jet diesel people with 30 mpg are using, but I am just getting
the regular diesel from regular gas stations.

How do you find out if you're getting good diesel with high cetane ratings? I'm always looking for it
at the pump, but I never see anything.

And as I posted earlier, my moms gasser got better mileage than my CRD on that long Highway trip, and I think at that point its kinda hard to justify a Diesel over a Gasser when looking at the price difference. Im not saying this is always going to be the case, these are just my first impressions since we only had both trucks for about 3 weeks.

Daniel

oldnavy · **Posted:** Thu Mar 09, 2006 12:10 pm

irunmiles wrote:

I have a long highway commute of 40 miles each way over flat roads, have 12,00 miles on the odometer, use the local truck stop diesel and add PowerSource centane boost with every tank, keep my rpms under 2000 - and still I only get 21-22 mpg. I'm also a professional engineer, so my math is correct.

Most truck centers sell 40 to 42 cetane fuel as that is what the big diesels OTR trucks are designed for, not the 50+ cetane fuel or CRD is designed for. From everything I have ever read or been told over the years is that the additives like PS grey bottle will not raise the cetane level if the diesel fuel was already treated with additives to reach the 42 cetane point. That was by a fuel/oil engineer a few years ago and I assume it still holds true today.

In years past I could not tell any difference in fuel eccomony when treating fuel with PS, all it seemd to do was quite down the ignition & IP noise some. The only time I could tell any real difference was switching to a higher grade of fuel that was cracked to a higher cetane then regular 42 cetane stuff. The old Amoco PowerBlend and Premieer come to mind here when it was available. Those two fuels would cause anywhere from 20 to 25% increase in fuel eccomony in my MB or VW diesels which were designed for 50 cetane fuel. The wost mpg's we have had was with the tank of BP 42 cetane crap the dealer fill our CRD with when we bought the Jeep. The CRD was really a smoker and raddled like hell when started till well run it almost empty and put 19.5 gallons of 49 cetane B10, after that it quitened down and fuel mileage as been steady 22 mog with wife driving and has been a steady 30 to 32 mpg on the highway. I suppect you guys getting the poor mileage will see it increase once the 46 to 48 cetane ULSD fuel becomes the national standard. That said you will always have some retailer trying to make an extra buck by cutting the fuel with anything from kerosene to used motor oil, I have had that happen several times over the years.

PS: Dan I wasn't trying to call you an idiot, I guess it is too easy for me to sound rather gruff when writting, sorry about that. I have a college instructor friend with two masters degress that always just figured his mpg's by just his gage alone, I never could get him to understand that the fuel gages are not that accurate to figure mpg's for some reason. His new car has the computer that tells him his mpg's and that is all he uses and has never checked it to see if it is accurate.

omniphil · **Posted:** Thu Mar 09, 2006 1:06 pm

Hmmm, yeah so how do we know what cetane level the gas is that we are pumping into the CRD?

And also, if you've only have the truck a few weeks, you will need to wait longer on the CRD for the mileage to get better vs the V6, diesels need a longer break-in...

retmil46 · **Posted:** Thu Mar 09, 2006 1:07 pm

Yep, without cetane ratings on the pump, it's a hit or miss proposition getting good fuel without having to call the station owner and asking for the ASTM sheet listing the cetane rating.

I have seen as low as 22 mpg highway, #2 diesel from a Citgo outside Nashville TN, and an Exxon in Little Rock AR. Same trip, I exceeded 30 mpg highway on local B20 and Diamond Shamrock TxLed from the area east of Dallas.

Oldnavy's right, until ULSD comes on line and it's pretty much mandated what the minimum cetane level is that everyone has to provide, it's going to be a crapshoot as to what you get for fuel mileage.

omniphil · **Posted:** Thu Mar 09, 2006 1:09 pm

retmil46 wrote:

Yep, without cetane ratings on the pump, it's a hit or miss proposition getting good fuel without having to call the station owner and asking for the ASTM sheet listing the cetane rating.

I have seen as low as 22 mpg highway, #2 diesel from a Citgo outside Nashville TN, and an Exxon in Little Rock AR. Same trip, I exceeded 30 mpg highway on local B20 and Diamond Shamrock TxLed from the area east of Dallas.

Oldnavy's right, until ULSD comes on line and it's pretty much mandated what the minimum cetane level is that everyone has to provide, it's going to be a crapshoot as to what you get for fuel mileage.

wow, that sucks.

I imagine performance is better with 50 cetane vs 42? Could we feel a power difference between the 2? maybe that would be a good indication of fuel quality?

I suspect a little watering down of fuel by gas staion owners? I mean if we have fuel/water seperators, why not add a little water in right?

And if thats the case, can i add my own water and save on fuel costs

retmil46 · **Posted:** Thu Mar 09, 2006 1:15 pm

omniphil wrote:

retmil46 wrote:

Yep, without cetane ratings on the pump, it's a hit or miss proposition getting good fuel without having to call the station owner and asking for the ASTM sheet listing the cetane rating.

I have seen as low as 22 mpg highway, #2 diesel from a Citgo outside Nashville TN, and an Exxon in Little Rock AR. Same trip, I exceeded 30 mpg highway on local B20 and Diamond Shamrock TxLed from the area east of Dallas.

Oldnavy's right, until ULSD comes on line and it's pretty much mandated what the minimum cetane level is that everyone has to provide, it's going to be a crapshoot as to what you get for fuel mileage.

wow, that sucks.

I imagine performance is better with 50 cetane vs 42? Could we feel a power difference between the 2? maybe that would be a good indication of fuel quality?

I suspect a little watering down of fuel by gas staion owners? I mean if we have fuel/water seperators, why not add a little water in right?

And if thats the case, can i add my own water and save on fuel costs

Actually, on that same trip, engine noise was a good indicator of fuel quality. On the high mpg brands, it purred like a sewing machine. With the low mpg brands, it clattered so bad pulling onto the interstate a couple of times it nearly scared the crap out of me.

valkraider · **Posted:** Thu Mar 09, 2006 1:19 pm

I wish people would just use the search function. This has been discussed over and over and over and over and over.

I think we need a "sticky" called "Bi weekly fuel economy debate".

People, here are two FACTS. There is no room for interpretation:
(note - there are many hyperlinks in my text, which may or may not be readily visible to you depending on your forum display settings. When you mouse over my text, the links will be highlighted)

1. Quality of diesel fuel will have a significant impact on diesel engine fuel economy. Fuel quality is often regional, and was also affected by Katrina and winterization. This is a big variable.

2. The Liberty has VERY POOR aerodynamics. The Jeep Liberty has a coefficient of drag of 0.421. That is TERRIBLE. Aerodynamic drag increases with the square of speed. According to Edmunds article Improving Aerodynamics to Boost Fuel Economy "Speed clearly is an important part of the equation. At stop-and-go speeds, drag isn't a big deal, but the faster you go, the more it matters. At 70 mph, you've got four times the force working against your vehicle that you have at 35 mph." What this means is that the faster you drive the Liberty the lower mileage you will get, and the impact is HUGE. In my own testing I found that mileage can vary from 33 at 60mph to 27 at 70mph. Additionally, I have no racks, and have not lifted my vehicle. A lifted vehicle, or one with light bars or racks will be more succeptible to aerodynamic effects at high speeds. Some people have found that simply installing the Renegade style light bar cost them 1mpg at highway speeds. Things like air density, humidity, and wind will also play a part in this...

Those two things are facts, and cannot be debated.

One of the biggest factors, I think, that CAN be debated - is what people call "highway" and "city". For me, my "city" driving is 100% stop-n-go short trip on surface streets. My "city" mileage sucks eggs. I am lucky to break 20 on my EVIC (which, as I stated in my other post that when compared to calculations my EVIC reads low, so I actually get slightly better than my EVIC readout). My "highway" driving is all trips, like skiing, or trips to the coast, or vacation. This means all interstate or open road at 50mph or better, with no stops. If there is no wind - I can easily break 30mpg on my EVIC.

I made a weekend trip of about 300 miles, which was mostly highway as I drove to a town on the coast then drove a little bit around the town then came home - and my average was 28. This was using 100% biodiesel, and my speed was never over about 65mph (usually around 60 - driving through the coastal range in Oregon 60mph is really good...) I made a trip up and down Mt. St. Helens area towing my boat (3500 lbs) and made over 26mog average. This included slow on dirt roads, some slight off-roading, and a good chunk of highway. This was using 100% biodiesel as well.

Additionally, the Sport version of the Liberty weighs less than the Limited, which combined with what you are carrying - can have an impact on fuel economy. Tires, their size, inflation, and type can have a huge impact on mileage as well.

And of course we throw in driving style and engine modifications and oil choice into the mix...

So it is very easy to get 30mpg but it is ALSO very easy to get 20mpg. It all depends on too many variables to say for sure what any one person WILL get...

oldnavy · **Posted:** Thu Mar 09, 2006 1:26 pm

valkraider wrote:

I wish people would just use the search function. This has been discussed over and over and over and over and over.

I think we need a "sticky" called "Bi weekly fuel economy debate".

People, here are two FACTS. There is no room for interpretation:
(note - there are many hyperlinks in my text, which may or may not be readily visible to you depending on your forum display settings. When you mouse over my text, the links will be highlighted)

1. Quality of diesel fuel will have a significant impact on diesel engine fuel economy. Fuel quality is often regional, and was also affected by Katrina and winterization. This is a big variable.

2. The Liberty has VERY POOR aerodynamics. The Jeep Liberty has a coefficient of drag of 0.421. That is TERRIBLE. Aerodynamic drag increases with the square of speed. According to Edmunds article Improving Aerodynamics to Boost Fuel Economy "Speed clearly is an important part of the equation. At stop-and-go speeds, drag isn't a big deal, but the faster you go, the more it matters. At 70 mph, you've got four times the force working against your vehicle that you have at 35 mph." What this means is that the faster you drive the Liberty the lower mileage you will get, and the impact is HUGE. In my own testing I found that mileage can vary from 33 at 60mph to 27 at 70mph. Additionally, I have no racks, and have not lifted my vehicle. A lifted vehicle, or one with light bars or racks will be more succeptible to aerodynamic effects at high speeds. Some people have found that simply installing the Renegade style light bar cost them 1mpg at highway speeds. Things like air density, humidity, and wind will also play a part in this...

Those two things are facts, and cannot be debated.

One of the biggest factors, I think, that CAN be debated - is what people call "highway" and "city". For me, my "city" driving is 100% stop-n-go short trip on surface streets. My "city" mileage sucks eggs. I am lucky to break 20 on my EVIC (which, as I stated in my other post that when compared to calculations my EVIC reads low, so I actually get slightly better than my EVIC readout). My "highway" driving is all trips, like skiing, or trips to the coast, or vacation. This means all interstate or open road at 50mph or better, with no stops. If there is no wind - I can easily break 30mpg on my EVIC.

I made a weekend trip of about 300 miles, which was mostly highway as I drove to a town on the coast then drove a little bit around the town then came home - and my average was 28. This was using 100% biodiesel, and my speed was never over about 65mph (usually around 60 - driving through the coastal range in Oregon 60mph is really good...) I made a trip up and down Mt. St. Helens area towing my boat (3500 lbs) and made over 26mog average. This included slow on dirt roads, some slight off-roading, and a good chunk of highway. This was using 100% biodiesel as well.

Additionally, the Sport version of the Liberty weighs less than the Limited, which combined with what you are carrying - can have an impact on fuel economy. Tires, their size, inflation, and type can have a huge impact on mileage as well.

And of course we throw in driving style and engine modifications and oil choice into the mix...

So it is very easy to get 30mpg but it is ALSO very easy to get 20mpg. It all depends on too many variables to say for sure what any one person WILL get...

What he says!!!

omniphil · **Posted:** Thu Mar 09, 2006 1:37 pm

Wow, lots of good reading

It seems like the only way to ensure you get good quality fuel is to make it yourself. I would seriously consider making my own biodiesel if I had any sort of storage area. I live in a townhouse and dont really have anyplace to setup a refinery

omniphil · **Posted:** Thu Mar 09, 2006 1:38 pm

Wow, lots of good reading

It seems like the only way to ensure you get good quality fuel is to make it yourself. I would seriously consider making my own biodiesel if I had any sort of storage area. I live in a townhouse and dont really have anyplace to setup a refinery

bigcanoe · **Joined:** Mon Oct 31, 2005 5:33 pm **Posts:** 96

Does Bio have an inherently higher rating?

valkraider · **Posted:** Thu Mar 09, 2006 4:40 pm

bigcanoe wrote:

Does Bio have an inherently higher rating?

Biodiesel has higher cetane than petroleum diesel, and also has higher lubrocity. However biodiesel has lower BTUs than petrolium diesel.

Although mathematically B100 should have around 4% less fuel economy than petroleum diesel, real world use has shown that results can vary greatly. The mpg can be affected by the oil stock used to make the bio, and the characteristics of the engine that it is used in, and how well the biodiesel is made.

Long commute vehicle?

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