Fuel economy

[Bill]

I recently put a new(rebuilt) 280SE engine in my 230SL. It runs fantastic but uses a lot of gas. I doubt that I’m getting more than 10-12 miles per/gal. Is this mileage normal for a 280SE? Bill

[teahead]

Any black smoke?

How are your spark plugs?

WOnder if you're running rich.

[Cees Klumper]

My 280SL averages around 19 MPG.

[Benz Dr.]

I get 10km per liter with my car. It is a 250 but a 280 shouldn't be that much less.

[roymil]

Milage of course depends a lot on how it's being driven.   I too have a 280SE factory rebuilt engine, with about 4K miles on it.   It has been getting 18-19 MPG driving up to ~60MPH around town, but that dropped to 15-16 MPG on a recent 500 mile jaunt at mostly 80MPH++ one day when I really was driving hard.   The only time I had milage around 10MPG was early on when I was messing around with FIP adjustments and idling it a lot.   Like they say, "Your milage may vary", but it does sound like your 280SE block is rich.    As suggested, confirm with the plugs.

This site has all kinds of help on many things that can make it run rich but I'd recommend first going back through the linkage and tune up tours and check all the easy stuff first.   My linkage was badly misadjusted after the SE block went in some 30yrs ago.  I also found the timing was way off and vacuum was leaking several places.  Then when I eliminated everything else I figured out the distributor was just a mess. I spent a day or two messing with the points and then I punted and bought a 123 ignition and that was a great decision.  It just works.  Good luck.

[roymil]

Dr Benz  ,  I just converted 10 km/liter and get 23.5 MPG!   Wow.  Thats awesome as long as its not too lean.  I don't question you at all, I've been reading and learning a lot from your posts and other vets on this site for the last 2-3 years as I bring my covid-pagoda back to life.   It's just that I can see now I have a lot more work to do to figure out how to improve my milage from where I'm at.  My plugs look great, exhaust gasses measure good so I thought I was done.  I guess I need to learn more along side Bill.  Appreciate any tips.  thanks

[lreppond]

I recently had a long block overhaul (Metric) and I’ve also had the FI system rebuilt/calibrated as well.  This past week I drove from my place in the East Bay up to Sonoma to show my dad his car.  I didn’t drive it hard at all, it was all flat driving and I don’t have A/C and the car has a manual transmission  My mileage was 25.4 mpg.  I can’t imagine ever getting better than that considering all the factors influencing mileage were in my favor.  I would think that if combined with a little city driving, it would be around what Cees’ car is averaging.

Mileage at the 10-12 mpg range seems suspiciously low…unless you’re driving it really hard and doing full throttle takeoffs or you’re in stop and go traffic. 

[H. Keith Henry]

Recently completed a 3,000+ mile trip and averaged 18.84 mpg going roughly the speed limit on mostly interstate roads. The middle third of the trip was handicapped by burned points (as reported in another thread today).

[rmunson]

After recent color spark plug tune up this spring, getting about 18 mpg driving mostly backroads around CT; some highway short distances.  Running great.  Using 93 octane high test.
1969 280 SL  77K miles.

[UJJ]

I get 20-22 mpg with my car.
4 speed manual with 3.27 Diff. Highway speed mostly 75 mph.

[Peter h]

Today 300 km from moselle ,france alsac to blackwood forrest Freudenstadt.
3.46 Differential
Nice sunny weekend to All.
Peter

[Desertpagoda]

16-18mpg is the best Ive EVER gotten over on 15 M130 cars in 35 yrs

[Revelstoke]

Have recently installed a new electronic ignition, air filter, plugs and wires. Using Chevron 94. Just back from a 1453km weekend of mixed spirited driving, and frustrating traffic,...the 230 didn't miss a beat and averaged 14.63 l/100km or 19.02 miles/imperial gallon. Definitely a little thirsty!