Poor Gas Mileage

[bubbl]

My '69 280 SL, which I have had for about a year, exhibits what I think is poor gas miileage.  I have never gotten more than about 15 mpg, with little difference between city and highway.

A few months ago, I had the engine and injector pump completely overhauled (The car had been in storage for a number of years, and there were corrosion and other serious prolblems  ~$20,000!).

Enigne and car now run very smoothly and quietly, with plenty of pickup, etc.  But the gas mileage has, if anything, become worse.  The injector pump has been carefully checked by someone I believe is a well-experienced mechanic, specializing in old Mercedes.

Is poor gas mileage a basic characteristic of this car?

Charles Ostrofe

[ctaylor738]

I would say that's about average, or a little better, for mixed driving.

[RonB]

When you did the pump - did you clean the injector lines?

Where the injectors check for spray pattern and volume?

This all make a difference.

[Cees Klumper]

My car has always gotten around 18 mpg (US) in mixed driving.
Compare this to around 27 mpg for my 272 hp modern Volvo S80 with its twin turbo straight six and substantially greater weight.

[Peter van Es]

I'm getting 16.9 mpg (US) on average for the least three years... (13.9 l / 100 km).

Peter

[batman]

The technical data contained in the Mercedes brochures for the 280SL claim a fuel consumption of 25 miles per imperial gallon/20.5 miles per US gallon at a constant speed of 100 KPH/68 MPH on even road.

[Benz Dr.]

The technical data contained in the Mercedes brochures for the 280SL claim a fuel consumption of 25 miles per imperial gallon/20.5 miles per US gallon at a constant speed of 100 KPH/68 MPH on even road.

That's possible but I'm thinking those figures are for a new car with everything working in top condition.

[49er]

 16mpg average for mine since getting the car back on the road. 99.9% of our driving these days is on 2 lane roads and at a "leisurely" pace. 20mpg+ sounds about right for when the car was new and driven frequently on the freeways. Those were also pre unleaded, pre ethanol days too.

John

[Rodolfo]

mine does 12l/km. Which would mean 23,5 mpg (imperial) Or 19,6 mpg (US).

On the highway it is even slightly better.

[enochbell]

At 15 mpg it sounds like you are on the low end.  Overhauled IP and engine may not tell the whole story.  Was the setup and adjustment done by an expert?  The linkage is very sensitive and you may just not be dialed in correctly.

g

[Benz Dr.]

I get around 10 km per liter or about 27 - 28 miles per imp gallon.

[alchemist]

I get about 16-17 miles/gallon for mixed driving with my 67 230SL that has M130 engine. I have another one with M130 engine, 1972 250C gets about the same.

[charlie]

If you think your fuel mileage Is still to much you can check the cold start valve . It has happened to me that the Cold start  valve has stuck on and then you will Use a lot of fuel.  Cheers Charlie

[pdc]

Reading this thread I got curious especially since my injection pump got overhauled and injectors tested so I decided to do find out what my consumption was.

had my red reserve light on for a while and filled it up : 71,18l
Drove 596 km and reserve light was on again when I filled it up again and the nozzle stopped at 67,13 L

Not sure I pushed more in after the nozzle stopped the first time
Not sure what was left in the tank when I refueled second time

Take the average of both refueling = 69,155 l

69,155/5,96 = 11,6l / 100 km

2.905893 gallon/62,1371 m

21,38 Miles / Gallon   ( hope my conversion is done correctly)

took pictures of everything to remember  

about the type of rides I did, mix of highway ( about 220 km at about 100km/h in one track) and several local trips thus with several cold starts.

Take a peek at the price per liter on the pictures.....

[kampala]

I think your math shows "imperial" Gallons.  In USA Gallons you are getting about 20.27 miles per USA gallon ---  very good mileage.