DCT / PowerShift Transmission Update TSB Thread

[dan50]

Originally Posted by kam327

"According to Fuely.com, overall economy for the 2012 Focus is essentially the same as for the Corolla. Considering the Focus is almost a different class of car from the Corolla, is more substantial, faster, etc., this is an accomplishment."

Yes the Focus is 0.7 sec quicker to 60 and 0.4 sec quicker in the quarter mile according to CR and still gets roughly equal economy according to fuelly users, but 12% less economy according to what I assume to be the more standardized testing of CR. The vast majority of folks aren't driving their Foci to the limits like that on a daily basis though. I bought mine for the balance of economy and comfort / handling, which I got but the DCT detracts from that experience.

Again, I still don't see good evidence of the DCT providing "class leading fuel economy". It can't match the Elantra's economy at 70mph even with the addition of the grille shutters and low resistance tires (according to PM).

Regarding fuel economy at 70, both the DCT and the Elantra's automatic with a lock-up torque converter have a direct connection between engine and drive wheels at that speed, so there shouldn't be fuel economy differences attributable to type of transmission.

Hyundais are notorious for not meeting their EPA estimates, but any difference vs. the Focus at highway speed is not a function of the DCT

[kam327]

Originally Posted by dan50

Regarding fuel economy at 70, both the DCT and the Elantra's automatic with a lock-up torque converter have a direct connection between engine and drive wheels at that speed, so there shouldn't be fuel economy differences attributable to type of transmission.

Hyundais are notorious for not meeting their EPA estimates, but any difference vs. the Focus at highway speed is not a function of the DCT

Dan50, not sure I understand your point. Please elaborate. If the Focus's tranny is supposed to be ~10% more efficient than the Elantra's conventional auto, the Focus has direct injection and variable valve timing, the car's weights are the same and Cd can't be too far apart, why shouldn't the Focus blow the Elantra away in economy? The point being that if Ford chose the DCT strictly for increased fuel economy, we aren't seeing the benefit in real world driving.

[TDiGuy]

The difference between the Elantra's transmission and the DCT is the Torque converter as you have already said. There is another difference too and that's the fact that a Torque converter must have transmission fluid which creates added drag on the drive line.

Looking at Fuelly right now and the average economy of a 2012 Elantra is only 30.8. I don't know who to believe but I tend not to trust CR on this issue. http://www.fuelly.com/car/hyundai/elantra/gas - actual data from hundreds of owners.

[kam327]

Originally Posted by kam327

Dan50, not sure I understand your point. Please elaborate. If the Focus's tranny is supposed to be ~10% more efficient than the Elantra's conventional auto, the Focus has direct injection and variable valve timing, the car's weights are the same and Cd can't be too far apart, why shouldn't the Focus blow the Elantra away in economy? The point being that if Ford chose the DCT strictly for increased fuel economy, we aren't seeing the benefit in real world driving.

Dan50, never mind I get it, at highway speed the torque converter locks up and the usual hydraulic efficiency losses are reduced / minimized.

But the Elantra, Corolla etc. still seem to be just as efficient in overall combined driving according to user inputs on fuelly, fueleconomy.gov, etc. Just not seein' the tangible benefit of the DCT.....

[kam327]

Originally Posted by TDiGuy

The difference between the Elantra's transmission and the DCT is the Torque converter as you have already said. There is another difference too and that's the fact that a Torque converter must have transmission fluid which creates added drag on the drive line.

Looking at Fuelly right now and the average economy of a 2012 Elantra is only 30.8. I don't know who to believe but I tend not to trust CR on this issue. http://www.fuelly.com/car/hyundai/elantra/gas - actual data from hundreds of owners.

Yeah, the Focus's average is also 30.8.

[TDiGuy]

Originally Posted by dan50

Regarding fuel economy at 70, both the DCT and the Elantra's automatic with a lock-up torque converter have a direct connection between engine and drive wheels at that speed, so there shouldn't be fuel economy differences attributable to type of transmission.

Hyundais are notorious for not meeting their EPA estimates, but any difference vs. the Focus at highway speed is not a function of the DCT

DCT = smaller, lighter weight, less power required from the engine to operate, no fluid to change, no power lost through a torque converter, fewer internal parts etc.

[kam327]

Originally Posted by TDiGuy

DCT = smaller, lighter weight, less power required from the engine to operate, no fluid to change, no power lost through a torque converter, fewer internal parts etc.

Exactly. Should result in better fuel economy all else being roughly equal.

This graphic from Popular Mechanics says it all for me. Very scientific comparison between the two cars. Lbs/hp is roughly equal, we can probably assume the drag coefficients and tire resistance are roughly equal if not favoring the Focus slightly. The Focus had the added benefit of the active grill shutters. The Focus engine has fuel saving technology (DI, VVT), not sure what the Elantra has. So with the DCT, where is the tangible economy benefit touted by Ford?

[TDiGuy]

According fuelly the Elantra averages 30.8. Where are the huge gains you keep referring to that give it the supposed advantage?

[TDiGuy]

I think it's quite an achievement for ford to get this type of fuel economy from a larger more powerful engine

[kam327]

Originally Posted by TDiGuy

According fuelly the Elantra averages 30.8. Where are the huge gains you keep referring to that give it the supposed advantage?

The Popular Mechanics graphic below - 70mph cruise - Elantra 39.3mpg / Focus 33.5mpg.

Actually I didn't say the Elantra had a huge advantage over Focus (at least don't think so), I was wondering why the Focus doesn't have a noticeable advantage over the Elantra (and others) given it's advanced, efficient drivetrain.