my E300D (95') is getting approx 27-29 mpg, mostly freeway driving with 50% AC running. I don't know if it's out of tune or something. It doesn't smoke much, runs pretty smooth with about 205K miles.

Any ideas? Not too sure what's in a diesel tuneup......

Check the simple stuff first, then the more complex/costly:

• Tire Pressures, personally I'm at least 5 over the suggested.
• Wheel Bearing Status
• Fuel filters - Main & Pre-filter recently replace
• Air filter too
• Proper oil change, synthetic here
• EGR/intake cleaned?
• Transmission Fluid/Filter
• Rear Differential fluid changed
• Type of fuel - Higher percentage of BioDiesel, lower mileage
• Limit A/C as needed - sounds like you are doing this
• Injection Timing?
• Injector Status - Tested, rebuilt/replaced?
• Driving habits go without saying
• Speed also factor

Seems like their are others with your model that are getting better, but that is fairly subjective and subject to wide variations. I've been doing too much city and short runs lately and am in the mid 20's I guess

Other will certainly add comments and some obvious misses of mine.

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raMBow

1999 E300DT Obsydian Black Metallic, Heated Full Leather Parchment options, E2, K2, 136,000+, best 36.5 mpg - GP's 12-04 & 11-12 Zero Stuck
2010 Honda Odyssey - The BrideMobile - best 26.5
(2) 2005 Honday Accord- (1 -Corporate 1 - Personal) - 110,000 4-cyl 30mpg
2000 VW Golf GLS TDI, Upsolute Chip (sold to Brother, now 300+k on it) 48.5 mpg like clock work
1987 Honda CRX HF - Sold 87,000 always over 50 mpg Max 67 mpg

On my diesels, when the mileage drops I start at the filters - air and fuel. Keep in mind, your mileage may be normal. I get 30mpg or so on the highway in the Texas heat cruising at 80+. In the city, 26 is about right. When the temps go down, the mpg goes up.

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- Brian


1989 500SEL Euro
1966 250SE Cabriolet
1958 BMW Isetta 600

I get 30 on the highway at best 27 to 28 in town. My wife gets a little better inthe 97. Like everyone else check the basics first. If your mileage is consistant then it may be as good as it gets. has there been a change in your mileage?

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Keith Schuster
2006 E350 98K miles
2013 Ford Explorer 15K miles

I used to get around 32MPG a few tanks ago.

I did some of the easy stuff recommended in the post above, I am going to do the rest.


Inlet manifold and EGR valve, how do you clean those?
thanks

I have a 95 with 222k on it - I get 32-33 on a highway cruise (80mph, AC on), and around 30 for normal driving (mix highway and city, AC on) in North Carolina (hot/humid summers).

I always use synthetic oil (I like Amzoil) - makes a difference (at least in my mind). Also, I always throw in some diesel fuel additive to help ensure injectors/lines stay clean, add some lube, eliminate water, etc. The minor additional cost doesn't bother me - I'm more interested in longevity of the car...

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1995 E300D - 225,000 miles - White Exterior, Grey Interior - original owner

Not certain about the earlier 606, her is a link that both touches on yours and then a link contained within for the newer models. It's really the complete glowplug removal process, but this is the first step of it.

http://www.peachparts.com/shopforum/showthread.php?t=119148

Hope this helps.

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raMBow

1999 E300DT Obsydian Black Metallic, Heated Full Leather Parchment options, E2, K2, 136,000+, best 36.5 mpg - GP's 12-04 & 11-12 Zero Stuck
2010 Honda Odyssey - The BrideMobile - best 26.5
(2) 2005 Honday Accord- (1 -Corporate 1 - Personal) - 110,000 4-cyl 30mpg
2000 VW Golf GLS TDI, Upsolute Chip (sold to Brother, now 300+k on it) 48.5 mpg like clock work
1987 Honda CRX HF - Sold 87,000 always over 50 mpg Max 67 mpg

My 96 E300 gets 36mpg on these flat Florida highways @78mph a/c on of course, but mid 20's for the the normal short hop driving. White car with 35psi all around and auto trans.

I have said this before but diesel cars seem to be more sensative to fuel quality than gassers. My E300 has been known to have gotten much better mileage from one brand of fuel than from another. If you suddenly notice an issue like this which happens on more than one tank of fuel and you buy fuel from the same source try switching suppliers (brand or just another station).

It's possible you just got some bad fuel the last couple of tanks and need to get it all out.

I've had my '98 for about a year and a half...when I bought it I was only getting mid to high 20's, now I regularly get high 20s to about 30 in mixed driving and low to mid 30s on the highway. I attribute that to it taking a year to blow all the crud built up from the PO's "weak" driving habits.

It's the only car I have owned that actually has gotten BETTER with age

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz