XDS...... Am I Imagening things

[Ess_Three]

I thought thats what ESP did?  In fact Im pretty sure thats what ESP does.

Nope, ESP brakes opposite wheels to counter a skid, and monitors yaw and steering angle to determine if the car is either under or oversteering. ESP can also cut power...but it doesn't try to stop the unloaded wheel spinning like XDS does, as ESP is only really triggered based on steering angle/yaw.

They do similar things in many ways...but ESP won't activate on straight line accelleration like XDS does.

[Ess_Three]

ESP = Electronic Stability Programme...only concerned with straightening up a car that's lost it's stability and is no longer on it's intended path.
It's a safety system, not a traction  system.

XDS is a traction improvement...and does absolutely nothing to stop a car going sidewards when out of control.

They both use the ABS system for information though, and the ABS controller to activate the individual brake callipers.

[Phil1980]

Cheers for that

[dubber36]

They do similar things in many ways...but ESP won't activate on straight line accelleration like XDS does.

They how come with the ESP on my Passat won't work on a rolling road (or spin the front wheels on sheet ice for that matter)? It is sensing a greater difference in front to rear wheel speeds therefore putting the brakes on and killing the power.

[Ess_Three]

They do similar things in many ways...but ESP won't activate on straight line accelleration like XDS does.

They how come with the ESP on my Passat won't work on a rolling road (or spin the front wheels on sheet ice for that matter)? It is sensing a greater difference in front to rear wheel speeds therefore putting the brakes on and killing the power.

No idea...is it broken?   
Does it have traction control? TCS/ASR?
They'll cut the power if the wheels spin...they are pretty crude.

My last few cars with ESP have all been able to be run in a dyno with it engaged...but it's generally better to disengage to get more predictable runs.

[nr123]

ESP incorporates traction control, stability control and EDL (electronic differential lock). EDL is a Mk5 thing and sounds very similar to XDS. The car can sense one wheel is spinning more than the other and transfers power (through braking) to the other wheel. That's what the grinding noise is on the Mk5 when you're in snow or ice.

[Ess_Three]

ESP incorporates traction control, stability control and EDL (electronic differential lock). EDL is a Mk5 thing and sounds very similar to XDS. The car can sense one wheel is spinning more than the other and transfers power (through braking) to the other wheel. That's what the grinding noise is on the Mk5 when you're in snow or ice.

ESP may well include the others...but not XDS, that's a different system.
EDL isn't a Mk5 thing either...my Mk3 16v has it, it was released in 1994 in the Mk3 16v!

XDS seems to be a more advanced version of EDL...but one that doesn't cut out at 30 MPH as EDL does...and is far more subtle in it's activation.

[AlanD]

Ahhhhhh thats right. I remember the man at Audi explaining it all when I was a driving course with them. Just couldn't remember it and for some reason thought he mentioned individual braking of wheels (which he obviously didn't).

Good work on the explanation