DSG higher C02's ... why ?

[Steamfan]

Why are the C02s on the DSG  higher than a manual  PD 1.9. its the same exact engine on both. Fail to understand how the gearbox effects the combustable operation of an engine?

[Stu vRS]

It's the same on the vrs. Tax is about 20 quid more for me than the petrol manual equivalent.

[Guest]

The DSG like a normal automatic vehicle uses more fuel than a manual on the test bed, therefore the CO2 will be higher and so the Road Tax will be more.

 

The size of engine even with the same specs when fitted with a DSG or an automatic is always different, the combustable operation of the engine will make no difference, it is the difference in amount of fuel used,i.e. the same as heavy foot or light foot on the throttle increases the CO2 level..

 

Fortunately we have not reached the point yet where all vehicles are fitted with a black box that records your actual CO2 levels for the year and your tax adjusted accordingly.

[JBD1974]

I'll happily be corrected but I think it depends on which dsg it is. The 6 speed had a wet clutch and the slight increase in drag that goes with it, whereas the 7 speed has a dry clutch (same as a normal manual) so it's a bit better for MPG and co2.

[nick74]

 

 

Fortunately we have not reached the point yet where all vehicles are fitted with a black box that records your actual CO2 levels for the year and your tax adjusted accordingly.

 

I suppose arguably they don't need to go that far, the more fuel you burn (and thus the more CO2 you produce) the more often you need to fill up at the pumps and therefore the more road fuel duty and VAT you pay.

[Kiwibacon]

Because the DSG box is less efficient at transmitting power.  That ultimately means higher fuel consumption.

 

The hydraulic pumps inside don't run on fairy dust.

[reverse]

Or just think about a simple thing called gear ratios...

[Kiwibacon]

Or just think about a simple thing called gear ratios...

 

DSG vs Manual gear ratios are the same in many cars.

[littleade]

Think you'll find th dsg box is heavier too which increases mpg over the manual.

[reverse]

DSG vs Manual gear ratios are the same in many cars.

 

Yes, but not on the car this topic is about. I think it was Autoweek website where they claimed that DSG box Octy (1.9PD) going 120km/h will have around 3500rpm. As the manual only had 2500rpm. That is a huge difference.

[booke23]

Yes, but not on the car this topic is about. I think it was Autoweek website where they claimed that DSG box Octy (1.9PD) going 120km/h will have around 3500rpm. As the manual only had 2500rpm. That is a huge difference.

 

That can't be correct. They must have left it in 'sport' or something (it won't go into 6th gear in S). At 75 mph on the speedo, my 2.0PD DSG is only at 2300rpm or thereabouts. 

 

The slightly higher CO2 emissions on the wet clutch DSG is nothing to do with it being less efficient at transmitting power.....it's actually more efficient at transmitting power during acceleration, which is why the DSG versions have the same or slightly quicker acceleration than their manual counterparts and why they are used in super cars a lot.

 

The higher CO2 emissions are due to losses from spinning a clutch immersed in oil, and driving a hydraulic pump in the gearbox.  

[Metblackrat]

Surely manuals are heavier? They have an extra pedal!

[Kiwibacon]

That can't be correct. They must have left it in 'sport' or something (it won't go into 6th gear in S). At 75 mph on the speedo, my 2.0PD DSG is only at 2300rpm or thereabouts. 

 

The slightly higher CO2 emissions on the wet clutch DSG is nothing to do with it being less efficient at transmitting power.....it's actually more efficient at transmitting power during acceleration, which is why the DSG versions have the same or slightly quicker acceleration than their manual counterparts and why they are used in super cars a lot.

 

The higher CO2 emissions are due to losses from spinning a clutch immersed in oil, and driving a hydraulic pump in the gearbox.  

I do agree with 3,500rpm being an obvious and glaring error.  But how do you claim it's more efficient at transmitting power, then admit to these other oil-churning and pump-driving losses at the same time?  It's the oil churning and pump driving that makes it less efficient at transmitting power.

 

That's like claiming I'm a millionaire, then adding as an afterthought that I borrowed 990,000 from the guy down the road.

 

The higher CO2 emissions are because it's less efficient at transmitting power.  It's less efficient at transmitting power because it's got more parts rotating in oil (power loss right there) and has to drive an internal hydraulic system (another power loss right there).

[mikey vrs]

Just got my renewal for my 2008 manual TFSI octavia vrs.....£260 for a year! :-(

[lol-lol]

Why are the C02s on the DSG  higher than a manual  PD 1.9. its the same exact engine on both. Fail to understand how the gearbox effects the combustable operation of an engine?

 

The six speed wet multiplate auto gearbox on the Octavias and Superb takes more power from the transmission to the wheels than the manual, it is also a few kilos heavier which effects the urban fuel consumption particularly.

 

There is a better box than this DQ250 ie the DQ500/1 which is more efficient and hopefully Skoda will start to get it soon.

[Staedtler]

Mainly, the gearbox is heavier (+35kg).

All being said, if ratios are the same, I doubt gearbox friction will be that much different.

The reduction you see in CO2 on some gearbox's is down to either different ratios over a manual for the official rating or the fact it is programmed to change up much earlier than most people do in a manual box.

In the real world, unless you go with the flow all the time with dsg and normally have a heavy right foot, I suspect a well driven manual will be more economical.

Also you can coast in a manual, whereas only the very latest DSG's can do this...that has quite a markes afcet on economy.

[booke23]

I do agree with 3,500rpm being an obvious and glaring error.  But how do you claim it's more efficient at transmitting power, then admit to these other oil-churning and pump-driving losses at the same time?  

 

It's all down to what you mean by "more efficient at transmitting power".

 

If you apply full throttle from a standing start on a DSG, it is more efficient at transmitting this power.....because unlike a manual there is no coasting involved every time it changes gear.

Edited 7 August, 2013 by booke23

[Kiwibacon]

It's all down to what you mean by "more efficient at transmitting power".

 

If you apply full throttle from a standing start on a DSG, it is more efficient at transmitting this power.....because unlike a manual there is no coasting involved every time it changes gear.

 

There is only one definition of efficiency.  Efficiency = Power out / Power in.   There is nothing more efficient than a manual gearbox for transmitting power.

 

Change time isn't related to efficiency.

[lol-lol]

I coast in my DSG, probably travelled hundred of miles with it in N, easy peasy lemon squeezy. Probably helps me get another 5 or 10 miles from a tank of petrol. Hand rests on the stock to move to D or S for engine braking or when I get to the bottom of the hill or need to squirt the car with some power again.

[booke23]

Change time isn't related to efficiency.

 

It is at the getaway from the lights! 

[Kiwibacon]

It is at the getaway from the lights! 

 

That's not efficiency though.  That's effectiveness.

Simple example.

If you need to get 400m away, a bicycle is the most efficient way to do it (least energy spent, don't care about time).  A rail dragster is the most effective way to get there (shortest time, don't care about energy spent).