Fuel Economics

Merco

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So the car was in for a service the last few days (C-Class Estate, 60 plate) and was lucky enough to get a similar C-Class Estate on a 60 plate as a runaround for a few days.

Big and noticeable difference though - Mine = C200 Diesel manual, replacement: C180 CGI Automatic.

Fairly comparable I think. My car has done around 17k and replacement 7K.

Difference in fuel economoy was considerable! I do a lot of runs up and down the A3 and in my own car I manage arond 47-50 mpg on that run and in the replacement it was more like 33 mpg.

Now, I'm not sure if that difference is due simply to mine being an oil burner or due to mine being a manual or maybe even to mine having loosened up a bit more. It may be all 3 but I am inclined to think that the diesel factor might stick a few mpg on there but perhaps the manual element sticks a few more.

Am I developing an argument here for manual cars!? Anybody convinced?
 

flango

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Am I developing an argument here for manual cars!? Anybody convinced?
Yep and that's one of the reasons I now never run an automatic. Used to run BMW's at one point :ban: 330i Manual petrol average mpg 37.5 Yet my 330i auto 2 years newer 29.5 mpg. Have never run another auto since that car.:thumb:
 

SPX

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Am I developing an argument here for manual cars!? Anybody convinced?
No.
A Mercedes without an automatic gearbox is like David Cameron without Nick Clegg.

What you have touched on in your comparison of two similar cars separated only by fuel type is that the diesel is 50% more fuel efficient.
 

flango

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Sorry I might have misread that are we talking cdi or cgi, the comparison above as stated is comparing diesel to petrol.

I agree an MB without an auto box is like cameron without clegg, a lot better :D nothing wrong with my manual MB :)
 

SPX

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Sorry I might have misread that are we talking cdi or cgi, the comparison above as stated is comparing diesel to petrol.

I agree an MB without an auto box is like cameron without clegg, a lot better :D nothing wrong with my manual MB :)
If the op is referring to everything else but Mercedes, then I'd say yes, manual gearboxes are better for fuel consumption and driver involvement...
 
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Merco

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I agree - I find manuals so much more engaging to drive. I enjoy that everythng on my Mercedes is automatic - wipers, lights etc but I want to engage with driving it too and the fuel economy is a relevant feature - even for a Merc!
 

Oli

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If the op is referring to everything else but Mercedes, then I'd say yes, manual gearboxes are better for fuel consumption and driver involvement...
I would never have a manual Merc and I find their auto boxes really good anyway, other cars though I agree, currently got an auto VW Golf and it's not great and the fuel economy for a 1.6 is poor.
 

st4

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Yep and that's one of the reasons I now never run an automatic. Used to run BMW's at one point :ban: 330i Manual petrol average mpg 37.5 Yet my 330i auto 2 years newer 29.5 mpg. Have never run another auto since that car.:thumb:
In the MBs auto may add 1-2mpg to the fuel bill. For the other advantages it offers as well as manual control over the box, I would say they make a welcome addition, however, as a believer in choice I feel it a shame you cannot get a manual transmission on any 6,8 or 12 cylinder Mercedes. I'd maybe consider one as the 7g is so crap and I can do a better job myself, (not something I'd say re the 5g box).

In the latest BMW's with the new 8speed ZF box due to the tall 8th gear, the autos are more efficient than the manuals?
 

Dryce

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I would never have a manual Merc and I find their auto boxes really good anyway, other cars though I agree, currently got an auto VW Golf and it's not great and the fuel economy for a 1.6 is poor.
I had a Honda 1.6 Civic auto that got 47mpg on long runs (measured by the petrol that went in the tank).

For a while I used a Fiesta 1.6 auto that was lucky to get 36 mpg on similar long runs.

Why? Well my view was that Ford just didn't care what crappy old 1.6 petrol engine unit they combined half heartedly with a rather undistinguished auto box. The previous Focus and Fiesta automatics were just dogs IMO. Current ones may bet better.

I don't think VW are particularly good at smaller auto cars either. I'd be wary of a Polo or Golf traditional auto (never tried a DSG so can't comment).

OTOH manufacturers such as MB are rather more committed to getting it right with autos.
 

Colin_b

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If the op is referring to everything else but Mercedes, then I'd say yes, manual gearboxes are better for fuel consumption and driver involvement...
In the past, that was true. Recent MB autos (the 7 speed) are generally quicker and more fuel efficient than their manual counterparts. Certainly the case with my SLK.
 

Oli

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I had a Honda 1.6 Civic auto that got 47mpg on long runs (measured by the petrol that went in the tank).

For a while I used a Fiesta 1.6 auto that was lucky to get 36 mpg on similar long runs.

Why? Well my view was that Ford just didn't care what crappy old 1.6 petrol engine unit they combined half heartedly with a rather undistinguished auto box. The previous Focus and Fiesta automatics were just dogs IMO. Current ones may bet better.

I don't think VW are particularly good at smaller auto cars either. I'd be wary of a Polo or Golf traditional auto (never tried a DSG so can't comment).

OTOH manufacturers such as MB are rather more committed to getting it right with autos.
I agree, the old VW auto box is awful, in fact I used to have a manual Audi A3 1.8T sport a few years ago so pretty much the same car as a mk4 Golf apart from the shape and it was easily better on fuel than the 1.6 I have now, I struggle to get more than 28 MPG around town and 35 out of it, still it's alot better than the E55 still:D.

I've driven a new Golf 2 litre diesel with the DSG and I thought it was really good, a huge improvement over the old gearbox in my car anyway!!.
 

JohnDeere8530

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modern autos are quicker and more fuel efficient than manuals. They are also more relaxing to drive. Makes me laugh when people opt for lots of options on the smaller Merc, like auto lights and wipers then say they want a manual gearbox. Why????? surely auto is more befitting to these kinds of cars
 

flango

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modern autos are quicker and more fuel efficient than manuals. They are also more relaxing to drive. Makes me laugh when people opt for lots of options on the smaller Merc, like auto lights and wipers then say they want a manual gearbox. Why????? surely auto is more befitting to these kinds of cars
I can't think of one auto that is quicker or more fuel efficient than it's manual counterpart. The best there is by a country mile is the BMW 8g box and although it's up there it is not quite as efficient as it's manual counterpart.

Don't get me started on the MB 7g box it's a complete dog and light years behind some of it's competitors and the fact you can't get a manual box on bigger engined MB's is quite frankly rediculous, just search the forum and see how many MB auto box faults there are, then go to the BMW forum and do the same you will hardly find any.

MB great in Manual and 5g auto box is good but them MB just completely lost the plot on auto's. I've seen 7g boxes fail as early as 35k miles madness :doh:
 

LTD

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Yep, one of THOSE !!!
I drive an S Class.

One should never contemplate any manual labour in an S Class.
 

flango

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I drive an S Class.

One should never contemplate any manual labour in an S Class.
On that I agree whole heartedly but it would have to have a 5g box:D
 

wkdc230k

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on that run and in the replacement it was more like 33 mpg.
33 mpg from a 180k that's not very good when I get 30 - 33 in my 230k auto and that is combined motorway and town and lot older car.
 

markjay

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The arguments against diesel, in spite of the better fuel consumption, and in some cases lower VED, tax, and insurance, are:

1. The car's initial purchase price - new or second hand - is higher than petrol, and repair bills (if out of warranty) can potentially be substantially higher (though scheduled servicing should be about the same). If your annual mileage is low, you will never re-coup the additional cost through fuel saving.

2. If you drive only short journeys, this may have a negative (and expensive) effect on diesel car equipped with DPF (the DPF can be disconnected on out-of-warranty cars, but at a cost).

On the other hand...

1. Diesel cars will have better second-hand resale value, so the depreciation needs to be compared carefully with that of petrol, as in spite of the higher initial purchase cost the diesel may still be overall cheaper.

2. If you only do very short journeys, then diesel engines suffer less than petrol engines from the effects of the cold cylinder bores being washed with fuel (in the case of petrol, the fuel washes away the oil - in the case of diesel, the fuel is oily).

So... the short answer is that if you do high annual mileage, go for the diesel. If you do low annual mileage but through few long trips, buy the petrol. If you do low annual mileage and short trips, the diesel won't save you money and the petrol will not like what you are doing to the engine. And always try and avoid cars with DPF...

My point? That there is no one-size-fits all solution to the age-old diesel vs petrol conundrum.
 

Dryce

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I can't think of one auto that is quicker or more fuel efficient than it's manual counterpart.
In terms of efficiency I wouldn't rate a CVT.

But having lived with a CVT (or rather SWMBO lived with it - I had occasional rights) I disagree as regards to 'quicker'. IMO to takes a good driver in a manual to beat a mediocre but committed driver in a CVT on a tight and challenging road.

And to a lesser extent the same is true of autos in traffic conditions.
 

flango

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33 mpg from a 180k that's not very good when I get 30 - 33 in my 230k auto and that is combined motorway and town and lot older car.
180k in my experience does 39 - 41 mpg no where near the 5g auto at 34 - 35 mpg.

My 230k heavily modded at 270 bhp does 34 mpg on my commute to work, my BIL 230k auto 31 mpg
 

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