fuel mileage test

[Benz Dr.]

I just got back from a trip to Hamilton, Ontario. I the way I stopped and filled my car with 91 octaine and set the trip meter back to zero.
On the way home I stopped again to fill up since the reserve light was on. The first fill was 46.84 liters and the second was 58.11  I changed my fuel tank to the 82 liter version last year so I could extend my range.
The trip between fill ups was 546 km which is 338.5 miles. 58.11 liters is 15.2 gal. US or 12.74 Imp.  This gave me 22.27 MPG US and 26.56 Imp. It was almost all highway driving at speeds ranging from 70 - 80 MPH. On my car with the 5 speed, 2.5 liter engine, and the 3.92 axle, I was running at 3,500 - 4,000 RPM most of the time. I've seen as much as 28 MPG at 90 - 100 kmh below 3,000 RPM.

I found that when I bumped my timing up to 37 degrees the mileage went up and so did the performance. When the car was new it was set nearer to 40 degrees by MB so there's more room but 94 octaine isn't as easy to find and I think it would need it to run properly up in that advanced timng range.

What sort of fuel consuption are you getting?

[badali]

Last year going from Butler Pa to Blacklick I got 24.5 MPG going 60-65 MPH. It was about 240 miles one way.  1966 230 SL

[Benz Dr.]

That's exceptional mileage. Any special driving or tuning tricks that you're using?

[Cees Klumper]

My mileage just seems to stay very consistently in the 7.5 km per liter range, in a mix of some city, mostly highway driving, the latter at speeds of around 120 kph.
My Camino surprised me by returning around 7 km per liter, highway driving at the same speed, but on a 7.4 liter V8 engine from 1973...

[jameshoward]

32 MPG on a motorway-only run. (Note: Proper British Imperial gallons, not those tiddly American ones).

http://www.sl113.org/forums/index.php?topic=16594.0

[bogeyman]

Going to PUB last year I got 16-17 MPG (800 miles) in my '69.

Coming home I got 20-21 MPG after Joe's "magic touch".

[badali]

I'm not driving hard and stomping on the pedal.  Just going at an easy pace.  I filled up the tank and got right on the highway with no stop and go traffic.  Joe Alexander check my linkage and how the car was running and said he wouldn't adjust anything.  The car has just 61,000 miles on it.  It appears that none of the factory adjustments have been fiddled with.  I get close to 20 MPG around home in mixed driving.

I wish I could get better milage from my 4.5 sedan.  I seem to drive it pretty hard because of the power.  I typically get 10-13.5 MPG on it...

[Jordan]

I haven't been keeping track lately but at last years PUB I averaged 22.5 MPG for the whole trip (806 miles), mostly highway and some in town driving.

[Benz Dr.]

I'm not driving hard and stomping on the pedal.  Just going at an easy pace.  I filled up the tank and got right on the highway with no stop and go traffic.  Joe Alexander check my linkage and how the car was running and said he wouldn't adjust anything.  The car has just 61,000 miles on it.  It appears that none of the factory adjustments have been fiddled with.  I get close to 20 MPG around home in mixed driving.

I wish I could get better milage from my 4.5 sedan.  I seem to drive it pretty hard because of the power.  I typically get 10-13.5 MPG on it...

I work on 4.5's sometimes and there's a number of things to look at. Fuel pressure is critical on that engine with too much being as bad as too little. If the rubbing blocks on the trigger points are worn it will change the duration signal at the injectors.

 There's two temperature sensors on the engine - coolant and air. They both have to be perfect or the engine will run rich. I changed the coolant one that was only off by 100 ohms and it made a huge difference. So, you can improve mileage somewhat on this engine but not into the 20+ range.

You should also check the vacuum functions going to the distributor. I've found that the ports are often plugged inside of the throttle housing. If the distributor isn't getting vacuum signals you won't see any timing advance and the engine will be very thirsty. 

Very nice cars those 4.5's and when tuned right they're also fairly quick - maybe 9 - 10 seconds 0 - 60.

[badali]

The car is pretty quick.  It will accelerate strongly even going up a steep grade.  I have to say it drives as good as any modern car and can hold its own in a rolling drag race.  From a standing start the weight holds it back a bit but it is still quick.  I have to check the sensors but I have replaced both the thermal time switch and the coolant sensor.  The vacuum lines and advance have been done also.  I have had the car for 15 years and it will get 13 mpg when I drive sensibly.  I put over 16K miles on it and it is at 84K now...

[Jkalplus1]

I have a 64 230SL rebored with oversize pistons, standard 4 speed transmission, euro model.

I used 50 litres for a 475km trip (10.5litre/100km, or 22.4mpg (US gallon).  Average speed 110km/h (driving anywhere between 100km/ and 140km/h) I used 94 (AKI) Octane fuel, no other additives.  I use up a little (20% more) city driving.

Oil consumption (10W40 with zinc additive from Hugues) is negligible over 1000 km.  It does not seem to have taken any at all.

Jerome

[Benz Dr.]

It would seem that 22 - 23 MPG is fairly common for a 230SL. My last trip was 9.3 liters per 100 km and I'm sure the 5 speed helped a lot for that. Before I changed my timing the best I could ever do was about 10.0 at slower engine speeds.
I'm going to try some 94 ( it's going to hurt at about 1.50 per liter ) and see if it makes any difference. Also, I'm going from my gauges in the car which may not be totally accurate. The next time I'm on the interstate I'll do a distance covered test. It could be 10% out or more. I do know it's better, all things being equal.


Your '64 should have header pipes. I wonder how much they factor into this?

[Jkalplus1]

Yes I have the header pipes, and my brother who rebuilt the head after I blew it (forgot to retighten after overhaul) told me the timing is a tad under 38 degrees. 

I am getting it in at Young St.. Garage in Ottawa for re-torquing the head, check the valves etc after the initial 1000km.  I am really hesitant to change anything considering how well everything works now, but the manual says to re-torque after 1000 miles or so and I want to avoid future unpleasantness as much as possible.

As for the 94 octane fuel, that's all I put in the car now.  I still had a very tiny bit of pinging on 91 on uphills when I floored it hard, but nothing at all with 94 so that's all I'll put in the tank from now on.

I am certain I can get even better mileage than what I reported above, but I don't intend to try:  I do not drive this car for its fuel efficiency, only for fun.  Different driving style!
J

[pj]

Hi Dan and Marcus and Brad and Cees and everybody,
sorry I didn't pick up on this thread last month. Since we left Dan's shop in early February, we have driven 4486 km and used 506 litres of fuel. That's 11.3 litres per 100km. Which is almost 21 mpg (U.S.A. gallons). The last tankful was 91 octane, after Dan made a few adjustments.

I'm just thrilled with how well the SL runs at pace, although now it idles about 1200 rpm and I confess I liked it better when it idled at 700. I won't blow away any Mustang GTs, but I can pull out and pass with alacrity when I need to. It's funny to compare it with the 2002 Acura, which I also love driving. I get a bit better than 8 L/100km in the Acura. Not bad for 200 hp at 7000 rpm. It sounds like a baby fighter jet compared to the SL. And my wife's 2010 Honda Fit hardly makes a sound at all -- the engine is smaller than her sewing machine, I'm sure.

[Oisin]

My 230 returns 22 mpg (imp) - it seems that most tend to.  I have to admit, now that petrol is £1.40/litre (8.3USD/US gallon), I'm using the Civic a wee bit more