You would think with a computer controlling gear changes it would be more economical than manual intervention but on paper it isn't......why ?

You would think with a computer controlling gear changes it would be more economical than manual intervention but on paper it isn't......why ?

Well one component of why the 6 speed DSG has worse fuel consumption than the manual version car is the extra weight of the 6 DSG gearbox. The 6 speed adds quite a bit more weight, about 35 or so Kgs which particular effects urban fuel consumption. Where there is an option to have the 6 speed DSG against a 5 speed manual then the the 6 speed DSG is quite a good choice if you do lots of extra Urban driving.

The 6 speed DSG uses two quite heavy wet multiple palte clutches as they could not get dry plate clutches to work in the smaller space.

The 7 speed DSG, despite having more gears, is much lighter and adds less overall weight than the 6 speed DSG. So with the combination of lighter unit and more gears the 7 speed DSG can improve fuel consumption by a mpg or 2 and lower C02 bands by one or 2 as well. Problem is that this gearbox can only handle 250 NM of torque so can be used on the more powerful 2 litre and above diesel or petrol engines.

There is an 8 speed DSG in the pipeline and software and other improvements should make autos better. The Fabia VRS I think will only be DSG like the Ibiza Cupra and in 5 or 10 years manual geaboxs are likely to be a rare option.

Edited 17 April, 201016 yr by lol

Good point. I suspect another reason is that the computer doesn't actually know what it is one is trying to do at any one time, it has to guess. In a manual one knows not only what one is currently doing but what one is about to do as well and anticipation is a key part of economic driving.

Good point. I suspect another reason is that the computer doesn't actually know what it is one is trying to do at any one time, it has to guess. In a manual one knows not only what one is currently doing but what one is about to do as well and anticipation is a key part of economic driving.

Well put. The DSG gearbox has all sorts of sensors including an inclineometer put it does not know what you will doing 50 meters down the road ie up hill, down dale. When I am driving some roads I use the tiptronic function. Particularly on the Welsh twisty roads just leave it in 5 th or 6th and let it stay there. I do not know how much energy it takes to change gear but there are some instance where I do not want it to keep changing even if the revs to drop down to 1400 rpm and the DSG would change. The DSG does learn and adapt change points with the drivers driving style but only within fairly set paraments. Have not driven the 7 speed yet but I think it will particualrly suit the 180 hp 1.4 TSI. All this said the 2,0 TSI has such a wide spread of power 1500 to 6500 rpm I hop gears all the time and a 7 speed manual would be good too!

Edited 17 April, 201016 yr by lol

I'm also pretty sure that what it says on paper is based on "ideal" driving by the manual gear box. How many drivers can manage that? Whereas with the DSG, the human intervention has been removed, so in real life it might well be better.

Has anyone had both then and can comment ?

Has anyone had both then and can comment ?

I have, though the new one is DSG and the CR engine, old one was manual with PD engine (both vRs). My driving style is completely different with the DSG, it encourages you to drive sedately though the power is there if you want it as is the manual mode.

On the whole, I would expect the DSG to be more economical based on what I've experienced.

I've got the 1,8TSi DSG (non paddle) and it's very good, although there are times when it does get it wrong, not spectacularly wrong but I find I have to go to manual mode to get it just how I want it.

For example steep hills such as Porlock & Countisbury in Somerset and Devon it gets wrong so I select manual for them or for a very quick overtake then I select the Sport mode.

Economy wise, I'm not overly impressed, but that's because I made the transition from Diesel to Petrol, I'd suspect that the Diesel DSG is better than the Petrol DSG for economy, a family friend always buys diesels with auto boxes because he reckons that an auto box is better with a diesel engine.

On a recent trip from Surrey to West Somerset/North Devon, I filled the car to the brim & went there, did the running around and I found I needed to refuel before I came back, again brimmed it & on the way back I used just over 33,3% of a tank of fuel, which considering it's a petrol car & I was doing between 70-80 most of the way up (apart from the towns, bottlenecks & roadside piggy banks zones) isn't bad.

The reasons I got the Petrol DSG is because:

1/ I've got a duff left leg so gear changes were becoming painful.

2/ I couldn't have the CR diesel engine

3/ I don't do the miles to warrant a diesel engined car.

I regret not staying with the diesel, as I love the economy of them & the pure punch of them, however I can't really justify the extra cost of the CR engine and as I generally change cars every 30-34 months & I don't think that I'd recoup the extra cost of it, so probably isn't worth it.

I'm also pretty sure that what it says on paper is based on "ideal" driving by the manual gear box. How many drivers can manage that? Whereas with the DSG, the human intervention has been removed, so in real life it might well be better.

That's a good thought.

Presumably when they do the official economy tests, whoever's driving the car during the test is changing gear at the exact optimum time?

Whereas with the DSG, the human intervention has been removed, so in real life it might well be better.

Human intervention has not been removed because a human is controlling the accelerator and brake pedals.

AFAIK the issues with any "auto" (I'm using the term loosely) gearbox are the additional weight and increased drag compared to a manual trans. That is rapidly changing and I'm sure as somebody else has pointed out traditional manual gearboxes will shortly start to become optional extras rather than the way it is at the moment. Economy of scale will push manufacturers towards only offering a single gearbox eventually and that gearbox will be some sort of auto.

Presumably when they do the official economy tests, whoever's driving the car during the test is changing gear at the exact optimum time?

I don't actually think that official tests are done with a driver out on the open roads. I think they're done in a factory in carefully controlled conditions to ensure repeatability.

I believe that's correct, they use a 'rolling road' so that the tests can be repeated time and again, without interference from traffic/weather/etc. I guess it means the standards should be common between different manufacturer's.

I just wish my car could achieve the quoted figures!

So how they know (on manual cars) when to change gear?

Do they have some sort of Euro-Stig who does it for all cars?

Or is it defined in some regulation somewhere that you always shift up at x rpm?

:wonder:

So how they know (on manual cars) when to change gear?

Do they have some sort of Euro-Stig who does it for all cars?

Or is it defined in some regulation somewhere that you always shift up at x rpm?

:wonder:

An explanation can be found here: My link

or if you're having trouble sleeping, then try here: My link

An explanation can be found here: My link

or if you're having trouble sleeping, then try here: My link

ZZZZZZ

I believe it's actually this one Council Directive 91/441/EEC that describes the test cycle.

But it still didn't answer my question - the bit about when to change gear is in Appendix 1 which just refers to a lot of tables and figures that I couldn't find on the page (on the English version, at any rate)

:wonder:

That's a good thought.

Presumably when they do the official economy tests, whoever's driving the car during the test is changing gear at the exact optimum time?

It is based on a driving simulation and not an actual driving. See this site. I have extracted the pertinent words so that you do not need to go off elsewhere unless you want more information. To me it is a waste of time, except as a very broad comparison of cars. I always try to find real life test results, but have to bear in mind that driving style is afr more of an effect. FOr example, driving with the window down, or with a heavy load of passengers or golf clubs, or with poorly inflated tyres, or a heavy right foot!

Urban Cycle

The urban test cycle is carried out in a laboratory at an ambient temperature of 20°C to 30°C on a rolling road from a cold start where the engine has not run for several hours. The cycle consists of a series of accelerations, steady speeds, decelerations and idling. Maximum speed is 31 mph (50 km/h), average speed 12 mph (19 km/h) and the distance covered is 2.5 miles (4 km). The cycle is shown as Part One in the diagram below. Extra-urban cycle

This cycle is conducted immediately following the urban cycle and consists of roughly half steady-speed driving and the remainder accelerations, decelerations, and some idling. Maximum speed is 75 mph (120 km/h), average speed is 39 mph (63 km/h) and the distance covered is 4.3 miles (7 km). The cycle is shown as Part Two in the diagram below.

Combined Fuel Consumption Figure

The combined figure presented is for the urban and the extra-urban cycle together. It is therefore an average of the two parts of the test, weighted by the distances covered in each part.

Who does the tests?

The testing is carried out either by independent test organisations, or by the manufacturers or importers themselves at their own test facilities.

How Representative of Real Life Driving are the Standard Tests?

Because of the need to maintain strict comparability of results achieved by the standard tests they cannot be fully representative of real-life driving conditions. Firstly, it is obviously not practicable to test each individual new car; thus only one production car is tested as being representative of the model and may therefore produce a better or worse result than another similar vehicle. Secondly, there are infinite variations in driving styles and in road, car and weather conditions, all of which can have a bearing on the results achieved. For these reasons the fuel consumption achieved on the road is unlikely to be the same as the official test results.

I believe it's actually this one Council Directive 91/441/EEC that describes the test cycle.

No, that directive covers vehicle emissions - "Council Directive 91/441/EEC of 26 June 1991 amending Directive 70/220/EEC on the approximation of the laws of the Member States relating to measures to be taken against air pollution by emissions from motor vehicles" which covers pollution from vehicles.

Whereas 80/1268/EEC is titled "Council Directive 80/1268/EEC of 16 December 1980 on the approximation of the laws of the Member States relating to the fuel consumption of motor vehicles".

Interestingly, section 6.2 states:

"6.2. Gearbox

If the vehicle is fitted with a manual gear change, the gear ratio used is the highest recommended by the manufacturer for driving at each of the test speeds. "

and

"6.3. Test procedure

6.3.1. Road test

6.3.1.1. Weather conditions 6.3.1.1.1. The relative humidity must be less than 95 % ; the road must be dry ; the road surface may, however, bear traces of moisture, provided that there is no appreciable film of water at any one place.

6.3.1.1.2. The average wind speed must be less than 3 m/s and gusts less than 8 m/s.

6.3.1.2. Before the measurements are taken, the vehicle must travel on the chosen circuit, at a speed close to the test speed, a sufficient distance for the running temperature to be reached ; in no case, however, must this distance be less than 10 km.

6.3.1.3. Test run

The test run must be such as to allow a steady speed to be maintained and must be at least 2 km in length. It must form a closed circuit and the surface must be in good condition. A straight road may be used provided that a run of 2 km is made in both directions. The gradient must not exceed 2 % between any two points.

6.3.1.4. During each test run, the speed must be kept steady to within ± 2 km/h. The average speed for each test must not differ from the reference speed by more than 2 km/h.

6.3.1.5. To determine the consumption at each reference speed (see graph below), four tests are performed ; two at an average speed less than the reference speed and two at an average speed exceeding the reference speed."

So by the looks of things, a physical road test is used for determining fuel consumption figures.

Has anyone had both then and can comment ?

I have had both and can say this. Both taxis. My Octavia sport 2.0 tdi DSG averaged 39 mpg taxiing. Now my 2.0 tdi 6 speed manual Ambiente is averaging 52 mpg. Incredible difference. It is also a much quieter and smoother engine and much quicker and more responsive.

I never really expected the manual to be so much better on fuel. It is amazing and saves me a couple of quid a day. You may think thats not much, but when you count it up daily/weekly/monthly its a big saving. I enjoy driving it a lot more too as the clutch/gearchange combination is fantastic.

I have had both and can say this. Both taxis. My Octavia sport 2.0 tdi DSG averaged 39 mpg taxiing. Now my 2.0 tdi 6 speed manual Ambiente is averaging 52 mpg. Incredible difference. It is also a much quieter and smoother engine and much quicker and more responsive.

I never really expected the manual to be so much better on fuel. It is amazing and saves me a couple of quid a day. You may think thats not much, but when you count it up daily/weekly/monthly its a big saving. I enjoy driving it a lot more too as the clutch/gearchange combination is fantastic.

But you're comparing the PD with the CR as well as manual with DSG? My new CR with DSG is more economical than my old PD with manual and the engine is still new!

But you're comparing the PD with the CR as well as manual with DSG? My new CR with DSG is more economical than my old PD with manual and the engine is still new!

Only 2 litre CR is the vRS so the comparison is PD DSG vs PD Manual... Although I would have thought that both engines would therefore sound like a tractor

Edited 18 April, 201016 yr by Raglits

No, that directive covers vehicle emissions - "Council Directive 91/441/EEC of 26 June 1991 amending Directive 70/220/EEC on the approximation of the laws of the Member States relating to measures to be taken against air pollution by emissions from motor vehicles" which covers pollution from vehicles.

Whereas 80/1268/EEC is titled "Council Directive 80/1268/EEC of 16 December 1980 on the approximation of the laws of the Member States relating to the fuel consumption of motor vehicles".

Well I got it from following this set of links...

From http://www.vcacarfueldata.org.uk/faq/:

Q: How is the fuel consumption test conducted.

A: The test is outlined in Directive 93/116/EC and provides results that are more representative of actual average on-road fuel consumption than previous tests. There are two parts: an urban and an extra-urban cycle. The cars tested have to be run-in and must have been driven for at least 1,800 miles (3,000 kilometres) before testing.

Directive 93/116/EC is also about fuel consumption - I think it's a modification of the 1980 one you linked to (which I'm guessing was the old version before the "extra urban" etc. was introduced)

And in that document,in the section about fuel economy testing, it says

6.1 Test cycle

The test cycle is described in Appendix 1 of Annex III to Directive 91/441/EEC including both Part One (urban driving) and Part Two

(extra-urban driving).

Which is where 91/441/EEC comes in.

Anyone else still awake?

Only 2 litre CR is the vRS so the comparison is PD DSG vs PD Manual... Although I would have thought that both engines would therefore sound like a tractor

I now have , well for the past 18 months/80k the CR 2.0 dsg passat, having previously had the older engine with manual 6 speed . The DSG/CR is around 5mpg better than the previous car and is much quicker too!

Both cars did similar mileage and personally I wouldnt go back to the manual box.

I now have , well for the past 18 months/80k the CR 2.0 dsg passat, having previously had the older engine with manual 6 speed . The DSG/CR is around 5mpg better than the previous car and is much quicker too!

Both cars did similar mileage and personally I wouldnt go back to the manual box.

What kind of MPG figures are you achieving ?

I know how to drive a car to get the best out of the fuel, and can say for sure that a manual is miles more economical than a DSG. People can argue and post comments as much as they like, makes no difference. My figures speak for themselves. They are also borne out by the fact that, being a taxi, it's running brim to brim full every day so i can get an accurate measure of mileage and cost of fuel each shift.

Try as i might i couldn't get the DSG to top 39mpg, yet 50+mpg is easily achievable in the manual with no difference in driving style.

Maybe the CR engine is better and more suited to the DSG, but my 2 140pd's, manual wins hands down.

The majority if not all users on this forum report that the CR is more economical than their old PD.

So just to clarify, what engine (CR or PD) and gearbox (manual or DSG) combinations are you comparing?

Edited 19 April, 201016 yr by Dodgy