I have been driving 1986 300E with 3 litre engine, for approx two weeks and have put approx 1500 KL (937 miles) by driving mostly (approx 90%) highway at speeds between 120 km/h to 135 km/h (75 to 85 mph) I am very pleased with the fuel consumption which after each refill has been a constant 27 mpg (imperial gallon) or 10 ltr/100km. --- (my car has approx 170,000 km, new cap and rotor, NGK platinum plugs, 10w-30 synthetic oil, tire pressure all around at 34 psi.)My friend who has a much newer 300E but with a 3.2 litre engine drives like a old lady in order to conserve fuel. On the highway he’s a rolling roadblock because he set's his cruise at 100 km/hr (62 mph). He tells me he's average is only around 22 mpg (imperial Gallon) or 12.8 ltr/100km.
would be interesting to hear the fuel numbers from others please advise if your numbers are per US or Imperial gallon. Remember that the Imperial Gallon is 20% larger.( Ltrs/100km is realy the standard and would be the easiest for comparison).

I've never heard of fuel consumption that low on an M103... how are you measuring?

I get a (mixed driving) steady 19mpg (aprox) with a good O² sensor.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

I see 20mpg highway and about 16 around town. 126 car.

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E

I get a consistent 22 in mixed driving with the CE

It seems the E only gets a little over 20 in mixed driving. The E gets 24 in highway driving.

Never had the CE go through a full tank with highway driving.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

Yes forgot to mention - had my car tested and was told that the original O² sensor was sending too much fuel so we tried a cheapy aftermarket which seemed to lean out the fuel mixture. Perhaps that's it?

Then I've got to start measuring in imperial to help conserve oil
That sounds a little more reasonable. On the highway (very rare for me to use a whole tank out there) I have seen about 23mpg.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

Right on 24 mp/us gal = 26.4mp/imp gal.
20 mp/us gal = 24 mp/imp gal
Your figures were in US Gallons - right?

Correct. Now ask me how hot my engine is in degrees fahrenheit and I will have to go get some conversion done.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

[COLOR=Navy]Please excuse my ignorance but are all M103 engines the same? My 1986 300E has a 3-liter. My friend’s 300E has a 3.2 and I have also heard that there is a 2.7? M103. Am I wrong?[/COLOR]

He..he.. I would not ask in F but in C degrees.

I'd like to share my results only my car doesn't start . Once the car starts working properly I'll share my results .

__________________
1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

there are 2.6, 2.8, and 3.0 m103's to the best of my knowledge. I think the 2.8 was just made in one year.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

There are 2.6's and 3.0's, but I think the 3.2 would be an M104. I would guess the 2.6's might get close to 27mpg (US) on the highway but I am not sure. The m104's (3.2 and 2.8) could probably get there though if the drivers boot wasn't too heavy.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

I've got the m103 in the 300SE (w126). I get around 17mpg city, 21 highway. The best milage I got was 26mpg, that was driving from Santa Cruz to south Orange County, never having to refill once. Only stopped once too. And most of it was downhill.

Fuel mileage varies DRASTICALLY depending upon, driving conditions, vehicle condition, vehicle maintenance and most importantly driving style.

I have kept very good records on my 300E to include every fuel stop that it has made in over 200,000 miles. I consistently get 25 to 27 mpg in mostly highway driving with the few times that I've done heavy stoplight to stoplight dropping it to 21 to 22.

That said, my car is a stick shift, so it will naturally be more stingy on fuel than the typical automatic cars.

Have a great day,