Driving the 6.9 daily

[s class]

Well, the 280SE is on stands this week awaiting new rear disks (sorry styria - I purchased locally - I think importing from you would be too heavy on the postage). While the car is off the road, I'm refurb-ing the air cleaner housing - pics to follow.

So all week I've been using trusty rusty as my run-around. Very nice. The engine is getting happier and happier. Presently it is using Shell Rotela diesel lube oil as a flushing agent. I'm enjoying the car a lot - I'm not enjoying the fuel comsumption, which by todays standards is nothing short of obscene.

BTW, a few weeks back I used trusty rusty to tow in the W124 TE I'm working on for a friend, so I know the answer to the philosophical question

"what is the fuel consumption of a 6.9 towing a 1700kg W124?"

 

[BenzBoy]

Well, the 280SE is on stands this week awaiting new rear disks (sorry styria - I purchased locally - I think importing from ouy would be too heavy on the postage). While the car is off the road, I'm refurb-ing the air cleaner housing - pics to follow.

So all week I've been using trusty rusty as my run-around. Very nice. The engine is getting happier and happier. Presently it is using Shell Rotela diesel lube oil as a flushing agent. I'm enjoying the car a lot - I'mn not enjoying the fuel comsumption, which by todays standards is nothing short of obscene.

BTW, a few weeks back I used trusty rusty to tow in the W124 TE I'm working on for a friend, so I know the answer to the philosophical question

"what is the fuel consumption of a 6.9 towing a 1700kg W124?"

Don't think of the cost; just enjoy the experience.
A certain Phantom does about 12mpg and that is without towing anything. $50 of petrol is almost enough to prime the Autovac.
Regards,
BenzBoy

 

[B13]

Mine is used daily. I get 11-12mpg.

I.

 

[s class]

Ian, I'm afraid that after about 500km of driving, I seem to be getting about the same as you.

 

[B13]

Its as good as it gets, brotha.

 

[s class]

Its as good as it gets, brotha.

OK but this has been at urban speeds in traffic sometimes. Would it get better on the open road, say at a constant 120km/h?

 

[s class]

I guess there were some advantages to the W140 S500 : 6.9 type performance for 280SE type consumption.

 

[B13]

OK but this has been at urban speeds in traffic sometimes. Would it get better on the open road, say at a constant 120km/h?

Yes I can get an extra 100km per tank if I can get it on a freeway at 100-110km/h for those 100km.

They're at there worst in stop-start traffic.

I.

 

[TJ 450]

It is a 1970's 6.9 Litre V8 with K-Jet afterall. When new, the fuel consumption would have been quite reasonable all things considered. However, when compared to a modern equivalent such as the W140, it starts to look quite sad. Suffice to say, I will not be using my 6.9 as a daily driver unless I have to, or go insane, whichever comes first.

Tim

 

[Michel]

I thought my 690SEL needed a tune-up badly when I realised that it uses much more fuel than the Silver Spur...
But from what I have read, I will not bother doing any tune-ups (it purrs like a kitten when gently driven and roars like a lion when you push that pedal)

 

[Styria]

Hi fellow 6.9 devotees -Commuting to my storage shed, and general suburban driving OUTSIDE busy peak periods, will always give me about 16-18 mpg each and every time.

Short distance commuting (with engine not getting warmed up properly) works out to 250 kilometers for every 50 liters - or maybe just a little better.

Open Road cruising at 110 - 130, has always been at between 19 - 21 miles per gallon. It will be very interesting what consumption will be like after the recent valve grind and de-coke and new injectors. Will keep you posted. Regards Styria

 

[B13]

I will not be using my 6.9 as a daily driver unless I have to, or go insane, whichever comes first.

LOL

As Cam and Oscar will testify, I am insane...

I.

 

[s class]

styria, I think you probably have a more diciplined driving style than the rest of us. Given how little 6.9 mileage I have under my belt, I'm tending to use the loud pedal more than I suppose I might if I was more accustomed to the car. Having said that, I always drove the W140 very hard, and the consumption was little worse than the 280SE - nowhere near as severe the 6.9s consumption.

In defence of trusty rusty, I know the valve timing is bad, and the injectors need replacing. I haven't checked the CO either. So no doubt there is some scope for improvement, but Michel, B13 et al are not exactly filling me with hope.

In any case, it is seriously fun, and so the consumption is moot. I can't however drive this car every day on a regular basis. This is just a little treat while the 280SE is off the road.

Another observation - I have become completely comfortable with the LHD steering - until I needed to pay a parking tab at the exit booth of a barking garage - need looooong arms....

 

[Des]

I guess there were some advantages to the W140 S500 : 6.9 type performance for 280SE type consumption.

I don't know what you guys are complaining about, the handbook for the 6.9 says 8MPG, so anything above that and your car is being frugal



For someone who drives 400-500k's a week it would be hard to justify that spending that much on fuel, even with such a great car as the 6.9

 

[Michel]

OK but this has been at urban speeds in traffic sometimes. Would it get better on the open road, say at a constant 120km/h?

Definitly better consumption on highway speeds....
Let us know...

 

[WGB]

Mine is used daily. I get 11-12mpg.

I.

Mine is significantly better than that.

I would say that 13.5 travelling in the hills of Perth, 14 mpg in around town running and 15 mpg cruising at 110+ km/hr. 16 mpg should be possible on a gentle cruise but I've never driven it quietly enough.

I know Perth traffic is easier than Sydney and I tend to drive when the roads are less congested - but I'm starting to think that I'm not driving it hard enough.

Bill

 

[s class]

After a week of driving trusty rusty I'm in serious danger of wanting to continue.... but risk of theft and the cost of fuel conspire against this.

6.9 is a very nice car to enjoy and enjoy and enjoy.

 

[Styria]

WGB -those figures you are quoting ought to be somewhat more representative of what a 6.9 should do according to Mercedes Benz. If I recall correctly, their figures range from 14 to 24 litres per 100 kilometers. It should also be remembered that the high compression engine is definitely more frugal - about three miles per gallon better that the OZ. version.

I recall an outing with the Ferrari Club up to the Hunter Valley and I did get up to speeds approaching 160. That day I got a bit better than 20mpg. A friend with an Oz. car got 17 mpg.

S - Class, I am surprised that it has taken you as long as a week to start appreciating trusty rusty or crusty rusty - I can never get that right. Anyway, 6.9's will do that sort of thing to you - the more you drive them, the more you start liking them, and also appreciate what they stand for. In my case, it took but 20 minutes.

One thing to remember regarding fuel consumption - it takes a fair bit of 'honing in' to get the car to do what you want from it. Also remember, they need to be driven. For instance, take a 400 km. round trip. I bet the second 200 will be more economical than the first, as the car, and the engine, settle down to the task on hand. Sometimes your mixture may need a slight adjustment after the first 200. It is surprising how things can be affected , but also improved upon.

I have to admit that I am fairly judicious in the way I apply the throttle. Yes, I do drive for economy, yet I am never left behind when it comes to driving in traffic. On the open road, I find that at 120 Gleaming Beauty seems to be just as, if not more economical, than if I was to stick to 100. Just my thoughts, Styria

 

[BenzBoy]

"I have to admit that I am fairly judicious in the way I apply the throttle. Yes, I do drive for economy, yet I am never left behind when it comes to driving in traffic. On the open road, I find that at 120 Gleaming Beauty seems to be just as, if not more economical, than if I was to stick to 100. Just my thoughts, Styria"
Simply NOT true.
Who is the man who howled down the M5 last year narrowly avoiding the mounted Police? If that was driving for economy then what is it like when you go on an Italian tune-up?
Regards,
BenzBoy

 

[s class]

styria, I guess my reticence about the 6.9 has revolved around the suspension - it behaves very differently to other cars, and I have remained fairly skeptical of its claimed superiority until recently. It also takes some experience to get used to the extra body roll. There are many times now I'm impressed by the hydro arrangement, but on the other hands still occasions I feel I prefer my 280SE's standard arrangement. The 280SE feels more confident at high speed - but to be fair, it has been completely rebushed - trusty rusty is still waiting for lower control arm bushes.

So during this first week of real use, I averaged about 23l/100km in a daily mix.

I filled up again this morning, and went on the first open road drive I've been on with the car - not really far - just to the west end of Pretoria and back - about 110km all in all, average speed about 120. Just from looking at the fuel level guage, I think the consumption was somewhat better than last week.

At 120 the car seems very 'busy' - not the effortless cruse the W140 gave. The plus side is that 120 is fast enough to feel fast and satisfy ones' craving for speed.

It constantly feels though that it wants more tyre performance. I'm using standard bundts with top end bridgestones in 205/70/14. I think I need the 15's with 225/60R15. Better tyres will also help with rear grip. Its fun to light up the rear now and then, but frankly the propensity to slide out at the back is a bit unnnerving, especially in the wet.

I also find that I can spin one wheel without too much difficulty - I guess this means the LSD clutches are worn out.