The definitive word on the "throttle lag" issue (hopefully)
 

So I just spent a good amount of time going through the 12 + pages of the thread about the dreaded throttle lag issue. I was also off from work today so I decided to do some experimenting.

Bottom line: There is no systemic problem here, individual defects notwithstanding.

There are a number of factors that need to be considered when looking at acceleration properties of the S6.

1. High power/torque. Proper engineering should allow for this power to be used when desired, but also allow for it to be controlled, made safe, and easily modulated for more mundane and practical transport needs.

2. Turbocharging. You can not expect this engine to react like a high revving, high compression or a big displacement normally aspirated motor. Until the boost kicks in, it is a medium displacement, lower compression motor. This is very typical for turbocharged engines and it is the price you pay in safety and reliability for that huge mid-range swell of torque. Low rpm throttle response will be blunted a bit.

3. Dual Clutch Transmission. Every dual clutch has issues in first gear off the line. With a proper manual, a human being can finesse the clutch/throttle relationship, but a computer can not do this. It can not act subjectively. It does one thing or another. This will lead to quirkyness from standing starts and coming to a stop.

4. Stability/traction control systems. This in relation to #1 above. Depending on what you do, and what mode you are in, these systems will interpret things differently, and react differently. If your driving style is not matched the the proper mode of the car, it will lead to a less than optimal result.

Anyway, based on these principles, here's what I disocvered today and what I have concluded.

The first thing I did was to do hard launches (without launch control) in D, S, then M. If you mash the pedal to the floor in D, the car bogs. This is when you experience the dreaded "lag". D is not meant to function for throttle mashing. The ESP is also in maximum sensitivity and power will be cut immediately so the wheels don't spin. Remember, these systems detect extremely minute amounts of spin or slide tendencies, long before you would actually feel it.

If you are in D, try this: do like a 2-3 foot roll out with light throttle. Then progressively push the pedal to the floor. You will launch very smoothly and confidently.

At the other end of the spectrum, I did launches in full manual mode with the ESP off. No initial lag whatsoever. The car just took off. Again, not like a high powered normally aspirated motor. It definitely took a little time to really feel the torque swell, but there was no lag other than the expected relative feeling compared to a turbo being on boost.

Adding in turning starts also led to varying results depending on the mode. Trying to drive gently in Sport, likewise, gave a lot of low speed jerkiness.

Bottom line: Use aggressive modes for aggressive driving and use gentle modes for gentle driving. It is when you don't follow this recipe, that the result is less than desireable. If you do follow this recipe, your car will respond exactly as the situation necessitates. Seriously, I am glad that there is "lag" in D mode. I would hate to be in bumper to bumper traffic and have the car leap forward with its 400+ lb-ft of torque at every jab of the throttle. It would be dangerous.

I didn't exhaustively read the other long thread, but it seems there are two issues that people are calling "throttle lag":

1. Lag off the line from a standing start, in the traditional sense of lag when talking about turbo motors.

2. Lag when getting on the throttle immediately after braking.

Your experiments are more relevant to case #1. I personally do not experience this at all and have great throttle response off the line either in drive or sport modes.

My issue is #2. It occurs in a straight line or in a turn. If you brake to slow down but don't come to a complete stop, and immediately try to accelerate again (either lightly, moderately, or aggressively), there is a significant lag, or pause, where there is virtually no reaction. It's as if the ECU is saying "you just applied the brake, are you sure you meant to accelerate again so soon?". After a couple seconds the motor responds as you would expect.

Once you get used to this, you learn to not try to scoot across traffic after slowing down, or pulling into traffic immediately after braking. I consider this a safety issue, but I also believe this was intentionally programmed in.

Safety issue?
 

I agree that its mainly the second circumstance. However, why would they intentionally program this in only the S6 and not in other (especially S series) models. Isn't it also a safety issue with the others?

I have no evidence, anecdotally or empirically, that it's an issue in other DSG/tip cars since my other car is a 6-spd manual. I personally think it's Audi's response to "unintended acceleration" issues that have plagued them in the past, and more recently Toyota, etc. Others will have to chime in whether other Audis behave this way.

It would be interesting to hear from S7, S8 and RS7 owners. These are the only "daily drivers" that have this level of power and torque. The R8 is a totally different beast with a NA motor at that, so it doesn't count. I think there are definite safety mechanisms built in to allow a car with this much power and torque to be driven safely, slowly and smoothly. Put it in the right mode for aggressive driving, however, and you are good to go.

Our S4 doesn't have the lag the S6 has. The S4 reacts as you would expect, and also has the benefit of the same (or similar) lightning quick shifts. The S6 is better in nearly all respects with the exception of the long delay before engaging the throttle.

The S7 owners have complained about the same thing. No idea about S8 though.

The only thing difinitive about this thread, is that it will become as long as the other thread that was not titled as difinitive :-)

I don't experience any throttle lag with my RS7 (nor did I with my Stasis A7, but that of course was supercharged so no boost lag). Now, I have the trans set on dynamic and I am usually driving in manual mode. After 40 years of exclusively manual transmission cars I still find it difficult to leave it in auto. When I do let the transmission do the work it is in S mode, I never have it in D.....

There is none of this throttle hesitation with the TT PDK, it's not inherent to a high hp/tq turbocharged engine or dual clutch tranny.

There is most definitely something wrong w/ the S6 in regard to this issue.