Why is DSG so punishing on fuel.............?

[GTR27]

The reason the 6spd dsg is worse on fuel than a 6sd manual is parasitic losses. The dsg isn't as efficient as a manual at transmitting power from engine to wheels. The reason why you are starting to see autos with better consumption is because manuals are still 6spd, while autos are slowly gaining more speeds. More speeds = better opportunity to pick the most efficient gear for the speed = better consumption. Torque converter autos by design will always have more losses than a manual due to how a torque convertor works. But more gears and advances in technology (shift logic, better lock up etc) means they are much closer than they used to be.

Back to dsg's, you will notice the models with 7spd dsg are more efficient than their manual counterparts. Two reasons - more gears and the dry clutch dsg is more efficient than the wet clutch dsg.

Edited 22 August, 2014 by GTR27

[JoseDB]

The reason the 6spd dsg is worse on fuel than a 6sd manual is parasitic losses. The dsg isn't as efficient as a manual at transmitting power from engine to wheels. The reason why you are starting to see autos with better consumption is because manuals are still 6spd, while autos are slowly gaining more speeds. More speeds = better opportunity to pick the most efficient gear for the speed = better consumption. Torque converter autos by design will always have more losses than a manual due to how a torque convertor works. But more gears and advances in technology (shift logic, better lock up etc) means they are much closer than they used to be.

Back to dsg's, you will notice the models with 7spd dsg are more efficient than their manual counterparts. Two reasons - more gears and the dry clutch dsg is more efficient than the wet clutch dsg.

But HOW is it less efficient at transmitting power?

Manual car = solid coupling via clutch

DSG = solid coupling via clutch (wet or dry - when it's engaged its solid)

Which to me says the reason the DSG is less efficient is a combination of more weight and poor gear choices by the software (maybe the EU tests highlight this and for once VAG have gone for making a software program that better in the real world than those daft tests). The only other possibility, which is entirely likely, is the DSG input shaft is harder to turn than that of a manual owing to the fact the DSG has a hydraulic pump and other bits to turn compared to a manual?

[lans]

Sorry to hijack the thread but the original is locked.

`Back to topic, does anyone find it interesting to note that the 1.4TSI units are rated at 140 bhp not 122 and that the DSG boxed 1.4 TSi is an old engine with only euro 2 emissions compliancy? All the diesel engined cars will be fitted with the cheaper rear axle, including the 150bhp unit?

Ian `

is this still valid?even for MY15?

[GTR27]

But HOW is it less efficient at transmitting power?

Manual car = solid coupling via clutch

DSG = solid coupling via clutch (wet or dry - when it's engaged its solid)

Which to me says the reason the DSG is less efficient is a combination of more weight and poor gear choices by the software (maybe the EU tests highlight this and for once VAG have gone for making a software program that better in the real world than those daft tests). The only other possibility, which is entirely likely, is the DSG input shaft is harder to turn than that of a manual owing to the fact the DSG has a hydraulic pump and other bits to turn compared to a manual?

Because the dsg clutches are wet (submerged in fluid), not dry (spinning in free air) like a manual. Spinning objects in fluid is much more difficult than air, as all fluids have a higher co efficient of friction. That is where the additional losses come from. It's not lots, but a few % which is reflected in economy difference between 6m and 6dsg.

Edit: of you Google, there are some efficiency ratings of each gearbox, and the dsg has more losses than the manual as above. Sorry I'm out in the country on a phone so can't provide more at the moment.

Edited 23 August, 2014 by GTR27

[JoseDB]

Because the dsg clutches are wet (submerged in fluid), not dry (spinning in free air) like a manual. Spinning objects in fluid is much more difficult than air, as all fluids have a higher co efficient of friction. That is where the additional losses come from. It's not lots, but a few % which is reflected in economy difference between 6m and 6dsg.

Edit: of you Google, there are some efficiency ratings of each gearbox, and the dsg has more losses than the manual as above. Sorry I'm out in the country on a phone so can't provide more at the moment.

Thanks, no need for more info. The answer is as I hypothesised, the gearbox is harder to turn

[fastestlouigie]

Sorry to hijack the thread but the original is locked.

`Back to topic, does anyone find it interesting to note that the 1.4TSI units are rated at 140 bhp not 122 and that the DSG boxed 1.4 TSi is an old engine with only euro 2 emissions compliancy? All the diesel engined cars will be fitted with the cheaper rear axle, including the 150bhp unit?

Ian `

is this still valid?even for MY15?

http://www.briskoda.net/forums/topic/287955-octavia-20-tdi-rear-suspension-torsion-beam-or-multilink/

I wouldn't think Skoda (or namely VAG) would be looking to change anything soon;Skoda and Seat are the value brands of VAG, so unless you fork out on a Scout or VRs, it will be Torsion beam rear. 'Course, you could "jump ship" and go for a Yeti, which has multi-link and torsion stabilisers (bit out of my depth here! )

[andyvee]

All that conjecture over made up numbers from lab conditions!

Sent from my HTC One_M8 using Tapatalk

[Telboy5]

My record for a decent run in my VRS TSI DSG has been 49.9,.....

 

I can easily achieve 45mpg+ on my runs so more than happy with the DSG performance thus far,...........

[Neily03]

My record for a decent run in my VRS TSI DSG has been 49.9,.....

 

I can easily achieve 45mpg+ on my runs so more than happy with the DSG performance thus far,...........

 

I was very tempted with the DSG but it was the expecation of figures like that that put me, I wanted my next car to be better on fuel than my last (mkII vRS CR manual).

 

My record is 60mpg on a journey and i regualry see low 50's on most journeys over 15 miles....

[KiDr]

well VRS TSI DSG is really not for economical driving, when i drive it i was to drive it fast, because speed is so effortless and fun in it and even when driven fast most of the time my average consumption after 5000 km is 7.5l\100, in your numbers i guess it is something like 38mpg. My other'scar Golf 1.2tsi average is 5.5l or 51mpg, and it is driven always smoothly. 10 extra mpg is not such a big price for fun:) Prior to VRS i had Outlander 2.4cvt it's average was 25mpg and it was fun only on frozen lakes:)

[lans]

http://www.briskoda.net/forums/topic/287955-octavia-20-tdi-rear-suspension-torsion-beam-or-multilink/

I wouldn't think Skoda (or namely VAG) would be looking to change anything soon;Skoda and Seat are the value brands of VAG, so unless you fork out on a Scout or VRs, it will be Torsion beam rear. 'Course, you could "jump ship" and go for a Yeti, which has multi-link and torsion stabilisers (bit out of my depth here! )

Thanks for your reply regarding the multilink. I think that 1.8 tsi get the multi link suspension aswell. I am not too fussed about that.

I was more interested in the 1.4tsi dsg being the older engine. because the manual 1.4tsi is euro 5 and the 1.4tsi DSG is euro 2(implying that it is in fact the older engine?)

http://www.briskoda.net/forums/index.php?app=core&module=attach&section=attach&attach_id=33980

maybe that is why the 1.4 dsg is fuel thirsty?

Edited 23 August, 2014 by lans

[Telboy5]

I was very tempted with the DSG but it was the expecation of figures like that that put me, I wanted my next car to be better on fuel than my last (mkII vRS CR manual).

 

My record is 60mpg on a journey and i regualry see low 50's on most journeys over 15 miles....

 

Neily,..I was quoting a petrol TSI DSG and 49.9mpg is actually really good,......

[gadgetman]

In the real world I don't think there is that much difference.

[fastestlouigie]

Thanks for your reply regarding the multilink. I think that 1.8 tsi get the multi link suspension aswell. I am not too fussed about that.

I was more interested in the 1.4tsi dsg being the older engine. because the manual 1.4tsi is euro 5 and the 1.4tsi DSG is euro 2(implying that it is in fact the older engine?)

http://www.briskoda.net/forums/index.php?app=core&module=attach&section=attach&attach_id=33980

maybe that is why the 1.4 dsg is fuel thirsty?

If you go to the SUK website through the link below then use the drop-down menu to get to the 1.4 with dsg, it reads as Euro 5, the same as the manual gearbox version. It also shows the other stats such as official economy figures (56.5 mpg combined-bet you'll be lucky to get 45....)

I'm pretty sure your reference (from the Octavia brochure?) is a typo-the brochures churned out by Skoda are notorious for mistakes!

http://www.skoda.co.uk/models/new-octavia-estate/performance

[Phil-E]

The 6 speed DSG has additional losses with driving an oil pump.

 

The clutches are then submerged in fluid. They are also very different to manual gearbox clutches and are made up of thin sheets of metal and clutch plates. They are then "closed" by applying oil pressure to them.

 

 

I think the most is down to just how the DSG performs in the test.

 

In the real world it's not too bad. Our old car was a Seat Cordoba PD130 6 speed manual and we were achieving an average of 44.1mpg. In the Octavia with DSG we are achieving 44.7mpg with the same driving pattern (mainly town runs with longer runs on a weekend and then Germany at least once a year).

 

Phil

Edited 24 August, 2014 by Phil-E

[Davey007]

Has anyone looked at the gear ratios between manual and DSG? I think it makes a difference in efficiency.

[Neily03]

Has anyone looked at the gear ratios between manual and DSG? I think it makes a difference in efficiency.

 

Yes, they're the same.

[conn]

I got 1.8 TSI 7 gear DSG. Factory claims 4.8 L/100. I do not have many steady long runs, but for notes last time I checked 150 km run from cold start with 3 adults, one child on board with around 50 kg stuff in the trunk. 225 17" wheels. There was 23C outside, so the AC was working as well. I had one city along the road for around 10 km (50 km/h with one traffic light stop), 10km distance was covered at 115 km/h. Rest of the way was at 93 km/h. I am talking about GPS speeds. Had few overtakes as well.

 

Bottom line - 5.5 L/100km at 0 m/s wind speeds.

 

For notes I have loosened up the engine by having over 15 000 km on the clock (done 2 oil changes one of which was at 6 000 km) and running octane 98.

 

I guess it would be possible to get close to 4.8 L/100 IF and only IF you are doing something like this: 16" 205 as standard possible, octane 98 half tank, driving alone (average weight man), windows closed, AC off, radio off, mirror heaters off, windshield heaters off (front and back), steady ride of 90 km/h on warm engine (oil at 100 or what not - mine runs at 103 on the highways). AND 0 m/s wind.

 

There is too many variables to that consumption number.

[Davey007]

Yes, they're the same.

I do not think so. Sorry I couldn't find a better source, but here are the other petrol engines: https://media.skoda-auto.com/en/Documents/Octavia_History/technical_data_new_octavia_petrol_en.pdf

[panmat]

My record for a decent run in my VRS TSI DSG has been 49.9,.....

 

I can easily achieve 45mpg+ on my runs so more than happy with the DSG performance thus far,...........

Struggle to get this with my diesel Vrs, and that is with a light right foot. Perhaps the roads are heavier here up north, must have some effect ???

[Sheldon.Cooper]

Has anyone looked at the gear ratios between manual and DSG? I think it makes a difference in efficiency.

 

Different ratios.

 

DSG is approx 20% higher.  (another reason the diesel 6sp DSG is worse than manual)

 

I've posted exact ratios on here before, go search for them.

 

Anyone who says they're the same is talking out of their bottom.

[KiDr]

today experimented a bit and in eco mode, driving very smoothly, not pressing but breathing on the throttle peddle i could easily reach 6.2l\100km or 46mpg. 

 

TSI Revo stage 1.

[marcusthehat]

The Honest John "real MPG'S" site is perhaps indictive.

Engine for engine, it appears to show DSG's about 3 to 5 mpg behind the equivalent engine manual in "real world" driving.

I get about 48ish on multiple short runs, mid-to high 50's on reasonable runs and can see 60 plus on long Sunday site-seeing pootles , but "going with the flow"

All trip figs, but only about 3% adrift from early days my anal retentitive brimming and calculating cross checking.

cheers

m

[Neily03]

Different ratios.

 

DSG is approx 20% higher.  (another reason the diesel 6sp DSG is worse than manual)

 

I've posted exact ratios on here before, go search for them.

 

Anyone who says they're the same is talking out of their bottom.

 

You won't let this go will you?

 

Can you please explain why both manual and DSG owners (diesel at least) get exactly the same revs in 6th gear at 70mph?

[JoseDB]

You won't let this go will you?

Can you please explain why both manual and DSG owners (diesel at least) get exactly the same revs in 6th gear at 70mph?

Different final drive in the diff...

See if all gears give same revs/speed to prove it.