Auto S or W? Idea to save fuel?

[Irishrebel]

Since fuel is getting so dear, I wonder why I changed from my 40mpg Audi 2.5 to a 30 mpg E300TD! Well, the Audi has a high mileage (I added 120000 over 6 years AND I suspect the previous owner clocked it VERY cleverly - it just feels old).

I believe 30 mpg is good for this car, especially with 146000 miles, but I find myself wishing for manual gears sometimes, when it just won't change up a gear that I would do manually. e.g. driving at 30 on a flat street, and I feel it would save more fuel if I could lower the revs.

Thinking about the S/W switch, the Winter mode is meant to allow upshifts at lower revs, so would keeping it on W save on fuel, or should it be kept for the winter? Thoughts?

Tim.

 

[Dieselman]

Maybe it will help but the car should pull 4th gear at 30 anyway as these cars are undergeared.

It will change up a gear at 1500rpm in either mode, once in it will hold that gear down to about 1200rpm then change down.

If it won't change up a gear then the engine torque is down a bit. Try flushing the engine oil with an extended flush and also clean the MAF sensor as this may be reducing torque.

The Audi was a direct engine and the E300 is indirect, so there is about 20% loss there.

Factor in overall running costs and I wouldn't be surprised if the Merc works out cheaper.

 

[seymansey]

I've just run my car this week in W all week. I lost about 30 miles somewhere and I've done the exact same motorway jaunts all week. Back to S for me.

 

[jadefox]

I find that unless you want to drive in a slow 'limo-like' mode while in W or C, that I tend to put my foot down a bit more to make up for the slow response - therefore negating any supposed fuel saving in the process!

I just stick to Standard mode - much happier

 

[Diesel Benz]

I find that unless you want to drive in a slow 'limo-like' mode while in W or C, that I tend to put my foot down a bit more to make up for the slow response - therefore negating any supposed fuel saving in the process!

I just stick to Standard mode - much happier

I agree. If the tranny starts on second gear at W-mode (I believe most do), there would be a lot more torque converter slip and power loss when pulling away. For a heavy car that increases fuel consumption easily more than lower gear change rpm would save.

Once the drive speed is reach, one can tap the gear lever and it will select a higher gear if at all possible. The W211 drives 50 km/h at 1000 rpm on 5th gear at even roads (I do it often in city driving). It even keeps the torque converter locked (mostly?) since there is hardly any load at that speed.

The 7G-tronic isn't that simple, it starts on second gear in C-mode and one cannot select S if one prefers the soft suspension mode. E-class is better as it allows the tranny and the suspension being controlled separately.

 

[Irishrebel]

Maybe it will help but the car should pull 4th gear at 30 anyway as these cars are undergeared.

My Audi could easily cruise in 5th at 30.

It will change up a gear at 1500rpm in either mode, once in it will hold that gear down to about 1200rpm then change down.

If it won't change up a gear then the engine torque is down a bit.

Must be something wrong: If I go up from 0 to cruise at 30 it sits at 1700 rpm. Just sounds too high. If I've got into higher gear then slow down, it seems to be OK. It was fully serviced in March when I bought it, so I'll wait for the next service to check this and follow your advice. A few thousand miles around France for 4 weeks will bring it closer.

I wonder how it will rev with a 25ft caravan behind it??

Tim.

 

[Irishrebel]

I've just run my car this week in W all week. I lost about 30 miles somewhere and I've done the exact same motorway jaunts all week. Back to S for me.

Lost 30 miles!

Do you mean 30 miles didn't show on your display that you believe you drove? Maybe you were abducted by aliens, and they dropped you off at destination to avoid the 'time loss' they've been accused of.

Or do you mean about 30 miles' worth of fuel?

Tim.

 

[Irishrebel]

I find that unless you want to drive in a slow 'limo-like' mode while in W or C, that I tend to put my foot down a bit more to make up for the slow response - therefore negating any supposed fuel saving in the process!

I just stick to Standard mode - much happier

So far I've found it OK. I worried that where I WANTED to accelerate quickly, I'd need S mode, but putting the foot down or kicking down produces plenty of speed. Getting onto a motorway can't be done slowly, all good drivers know, but I've noticed that changes ARE sooner, yet the final change at around 60 seems to take a little longer before it decides!

Pulling off in 2nd doesn't actually feel or sound any different than 1st for my car - suppose it's the huge amount of torque. I'll check the mpg at next fill and let you all know. Since I have 128 litres of Irish diesel behind the shed, it could be a few weeks!

Tim.

 

[Irishrebel]

Once the drive speed is reach, one can tap the gear lever and it will select a higher gear if at all possible.

By tap, do you mean push it down? I've read nothing about this in my manual, and I DID read it since this is my first auto. Maybe it's too old to have sophistications like that?

Tim.

 

[Diesel Benz]

By tap, do you mean push it down? I've read nothing about this in my manual, and I DID read it since this is my first auto. Maybe it's too old to have sophistications like that?

Tim.

Perhaps this feature came with W211, or was it already on the face lift W210? On a W211 you push the gear lever sideways to change gears up/down (within the limits the engine rpm at that speed allows). W221 and some sports/AMG models of W211 have steering wheel buttons for that.

 

[Irishrebel]

Perhaps this feature came with W211, or was it already on the face lift W210? On a W211 you push the gear lever sideways to change gears up/down (within the limits the engine rpm at that speed allows). W221 and some sports/AMG models of W211 have steering wheel buttons for that.

Ah no, the W210 that I have has the long gearshift that goes beyond D sideways to 4, then snakes down to 3,2, and 1. No 'tapping'! In D, it should use all 5 if it can, can't override.

Tim.

 

[Dieselman]

Just read this is your first auto. That alone counts for 5mpg so fits with the consumption increase over the Audi.

The Audi generated peak torque at a lower figure so would pull a higher gear.

You say you can't notice any difference when selecting W mode, you should eb able to. It may be stuck in W mode.
With the gearbox in N try flicking the switch, you should feel a change, also engage D then pull the stick back to 1 and you should feel a change.

 

[Irishrebel]

Check back!

I said I'd check back with this topic:

Thanks, Dieselman, but my car wasn't stuck on W. There's a clear difference in behaviour from S. Most annoying is because the change-ups happen earlier, they feel more clunky, like it's at the wrong revs.

Anyway, driving for a full tank to refill on W produced just over 32 mpg, as opposed to the usual 30 to 30.5 for me. Changing back to S, and trying to drive as softly, it fell back to 30, so for me, W means less fuel!

I don't 'overcompensate' for the lower revs on W by putting my foot down more. If anything, on S I tend to drive harder, if at all.

 

[Dieselman]

Interesting to note you have a difference in consumption in W mode as opposed to S.
I've just got back from a 186 mile round trip and calculate that I've achieved minimum 41mpg, maybe as good as 45mpg. I wasn't driving fast due to carrying something on the roof and calculating that it made only 10 minutes difference each way so not really an issue anyway.

Thought I'd just tell you that..

 

[merc180k]

To add my tuppence worth - I also find I have reduced mpg if using W instead of S. I tend to keep it in S but just drive like my old man!!

 

[glojo]

I said I'd check back with this topic:

Thanks, Dieselman, but my car wasn't stuck on W. There's a clear difference in behaviour from S. Most annoying is because the change-ups happen earlier, they feel more clunky, like it's at the wrong revs.

Anyway, driving for a full tank to refill on W produced just over 32 mpg, as opposed to the usual 30 to 30.5 for me. Changing back to S, and trying to drive as softly, it fell back to 30, so for me, W means less fuel!

I don't 'overcompensate' for the lower revs on W by putting my foot down more. If anything, on S I tend to drive harder, if at all.

You should get a better fuel economy when in 'W' or 'C' mode, BUT if folks don't like the slightly slower response, then by using a heavier right foot, they are negating any savings that might be acheived. If you are really interested in saving fuel, then the best and cheapest option is to improve our forward observation and anticipation! AND a slightly lower top speed

I think the 'tapping of gearlever' refers to the more modern tiptronic gearbox?

Regards
John

 

[nickcc101]

I use my w203 C180 in W but find (if not carefull) that i tend to use the kickdown more (booting to the floor) which of course uses more fuel than in s. My change in driving style has improved my average fuel consumption from 25mpg to 29mpg as long as i don't use kickdown and use the gear lever sideways selection to manually select a lower/higher gear.