Diesel RVs: Re: [diesel_mercedes] 350 SD Mileage

In my two 1983 w123 300d turbo's, I declare that I get 24-25 mpg all the time unless I am coming down from the Rockies. I believe that is what my owners manual says is "normal" under normal conditions.

brian from la verne, ca

From: Nate Rector <tccservice111@yahoo.com>
To: diesel_mercedes@yahoogroups.com
Sent: Friday, June 17, 2011 8:33 AM
Subject: Re: [diesel_mercedes] 350 SD Mileage

My SD hits 32 hwy,and with 50% wmo 34 hwy.

--- On Fri, 6/17/11, audiolaw@aol.com <audiolaw@aol.com> wrote:

From: audiolaw@aol.com <audiolaw@aol.com>
Subject: Re: [diesel_mercedes] 350 SD Mileage
To: diesel_mercedes@yahoogroups.com
Date: Friday, June 17, 2011, 10:24 AM

    I just rolled over 350,000 mi. on my way to Court on Tuesday! '81 300SD.

    I keep a three drawer toolbox and various other tools, spares, case of oil, some camping supplies in the trunk. So no lack of weight. I add almost 300 lbs each time I sit in the car.

    Regularly hover around 26-27 mpg in city driving, drift up to 29 on freeways. When we hit the road for a long trip, the mileage will get up over 30 and even over 31 sometimes.

    I know people who swear that they get 40+ mpg on their 123 cars, which are MUCH less aerodynamic than the 126s. I know people who swear that they get mid-20s on their Ford and GM V8 diesel pick-up trucks. I know people regularly see leprauchans on their way home from the bar, late on Friday or Saturday nights. I know people who swear that they know that dinosaurs and men populated the earth at the same time.

    I believe that progress happens, and that modern diesels are more efficient than our old ones. Does that mean that I believe that a 350 SD regularly gets 35 mpg? Remember what Teddy Roosevelt said: Trust but verify.

In a message dated 6/17/2011 5:42:03 A.M. Pacific Daylight Time, mahatmakanejeeves@yahoo.com writes:

A couple days ago a member posted that he calculated 30+ MPG for a 350SD. I have a '91 short body; my mileage on long-distance road trips rarely exceeds 26 mpg. That's at 5 mph over freeway speed limit, steady state with cruise control, for thousand+ miles. My calculation spans several fill ups, which compensates for variable top offs at intervening stops.

My '81 300SD rarely exceeds 27 mpg, same conditions.

I've noticed a roughly +3% calibration error to both cars' speedometers compared to GPS, so my MPG is overstated by a like amount.

How on earth would I get 20-40% additional mileage? Two answers obvious to me are: shed excess weight (like gutting the interior) and reduce rolling resistence (running on high-pressure, skinny tires). Oh, and setting the cruise for 40 mph for lower drag.

Is my car flagrantly out of tune on fuel/air mixture? I don't have soot belching out the tailpipe...

The car's PO had the notorious 3.5 L diesel replaced courtesy of Benz, thank you very much. But I assume the fuel injection has 189K chassis miles on it and I've never touched it.

MKJ