VW's 7-speed DSG more efficient than traditional automatics; *also permits gliding* - Fuel Economy, Hypermiling, EcoModding News and Forum

MetroMPG · 12-25-2007, 11:45 PM

It's clear a DSG will outperform a typical lossy automatic, so if people insist on driving the damn things, they may as well use this type (or CVT's).

Quote:

VW Golf: Coming with 7-speed DSG

For those not intimately familiar with VW’s DSG technology, the basic concept is relatively simple to grasp. Imagine a manual transmission, but instead of one gearset there are two - one for the even gears, another for the odds - and each has its own clutch. That clutch is computer controlled, as is the gear selection, so that while you are in second gear and accelerating, the computer has preselected third on the other gear shaft and only has to disengage the clutch from the active shaft and engage the clutch on the inactive shaft to change gears, allowing a seamless transmission of power between gears.

Aside from the efficiency gain of a direct motor/wheels connection (vs. a torque converter), the most interesting tidbit I learned is that the transmissions can be programmed to automatically de-clutch any time the accelerator is released... a true neutral glide!

I have read this was a feature that some drivers disliked on the super-efficient VW Polo model. Expecting engine braking and not getting it could be disconcerting.

And bonus: the speed freaks like the DSG gearbox too - because it makes the car faster than a traditional manual.

Here's a YouTube vid showing a DSG in operation:

DifferentPointofView · 12-26-2007, 12:27 AM

My mom has a CVT tranny on her vehicle, and what she doesn't like is she can't coast anymore like she could her old vehicle. That's it's only downside IMO.

MetroMPG · 12-26-2007, 01:25 AM

What kind of car is it?

DifferentPointofView · 12-27-2007, 01:06 AM

2007 Dodge Caliber R/T. It's got the CVT2 tranny with that autostick dealio. I enjoy the Autostick part

but coasting just isn't there like my big Jeep. She used to have a 2002 Dodge Stratus SE with the V6.

Who · 12-27-2007, 03:55 PM

I'd love to have that VW tranny... I was pretty sure it could coast (maybe I'll need to test drive another one) and I was under the impression that the only detraction was that it had to temporarily unload the power to shift unlike a CVT. It would be nice if transmissions could be independently tested for transfer efficiency, power required for pumping etc.

I'm waiting for the gear count wars to move down from just M-B and Lexus...