In general, I am always filling my car when the needle falls between the double lines near empty and recording between 15.7 and 16.2 gallons. For quite some time, I thought this must have been my fuel tank capacity...until this morning.

I leave for work each morning at 4:30am and like a moron, I didn't refuel last night. As I was pulling out of the drive, I noticed my fuel gauge and my trip meter read 500 miles, which is actually a little more than I normally drive on 16 gallons of fuel.

However, I remember reading the owner's manual and seeing the fuel tank capacity listed as 21.7 US gallons, so this morning, I decided to tempt the Diesel Gods and see how far I could go.

My 55 mile commute to work is highway all the way, so I just set the car on 65 and leave it there for the entire trip.

Based on my calculations, since I average 28.0mpg and have recorded a best-ever figure of 31.28mpg, I figured that I had a total cruising range of about 600 miles, but the owner's manual stated that the fuel capacity "is about 21.7 U.S. gallons," which doesn't exactly relate to a specific amount.

Nonetheless, it's cold, I have a quart of home-brewed french vanilla coffee and I am already past Visalia, California on westbound SR 198, so the next location where diesel is available before 8:00am is almost 30 miles away in Lemoore, California.

About 15 miles into my trip, the fuel guage needle lays down and stops moving; the low fuel diamond never lights up. However, we must still have fuel onboard because we are still cruising at 65mph without any issues. 45 minutes later, I roll into work with 557 miles driven on this tank of fuel.

By my calculations, I should have to put about 19.5 gallons in the tank to fill it, which should leave me about 2.2 gallons in reserve....

That should be enough to get to the diesel pumps on Interstate 5 in Coalinga...I hope...

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Having fuel left in the tank and getting it up to the engine without pulling air bubbles and causing fuel starvation are two different things. Your engine will die before you use up the full 21.7 gallons.

If you really want to drive it til it runs out of fuel. Buy a 5 gallon jug and fill it with diesel. Fill it with exactly 5 gallons. Put it in the trunk. Drive the car until it runs out of fuel. Put the 5 gallons in and prime the system and drive to the nearest fuel station to fill up.

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

Dad and I conducted a similar experiment once. We ran an electric switching valve and hooked into a (1) gallon can of diesel, then set the cruise on 65mph with all accessories off. Dad was careful to position the pickup in the bottom corner of the can and tilted it at an angle to ensure the car drew up every last drop.

The car ran 34.3 miles on (1) gallon of diesel at a steady 65 mph with the cruise control set. This was tested along a straight, flat section of Highway 198 near Lemoore, California. That was with only 500 miles or so on the rebuilt 617.950.

Wonder how much better (or worse) the mileage would be now with about 30,000 miles on the engine????...Robert

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

don't forget, that that one gallon can was not all the fuel in your car... the spin on filter had about a pint, and the prefilter had a bit, and the lines had a bit. so you probably got 5 or 6 extra miles worth of fuel there...

We cut the engine as soon as the clear line from the (1) gallon can showed bubbles...so, we did not burn up what was in the fuel system, as you correctly noted.

I get 28.0mpg on the average and a best of 31.28mpg...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Making the trip down to Lucerne Valley tomorrow....

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership