It is my understanding, after talking to a number of experienced drivers, that perversely, the car is safer in Sport and Sport Plus mode.
How is this?
Consider this situation. You have been driving along at about 60 to 65 on a single carriageway road. There is a slow car in front of you, you slow to 30 or so, waiting for an overtaking opportunity. The car thinks you are in traffic and puts you in the highest gear possible, keeping the revis at about 1500, for maximum torque and maximum fuel efficiency. You see a possibility and push down the loud pedal. There is no turbo lag, peak torque is from 1250 rpm. what seems to be turbo lag is computer lag as the engine and box work out that no you are not in traffic and want to go. So the box drops suddenly to 2nd or 3rd and with an open throttle and massive torque the car squats down on the bump stops, the suspension cannot cope and traction is broken: all power goes to one or other wheel. At that point you are a passenger as there is no traction control to help you.
Replay the same situation, but the box in in Sport +. This time when you slow the box holds a relatively low gear, because its program says "this boy is being sporty, so he may well need power soon". The engine is now at 3500+ rpm. You see the opportunity, push the loud pedal and there is no down change, the car surges forward on a wave of torque, without squatting on the rear bump stops and all is well.
The car needs better suspension, I hope someone is working on it.
The car needs to have power seriously limited when in normal Drive mode. I hope someone is working on it.
With the sort of suspension improvements SSL has brought to trads and now S4 Aeros the car would be rather nice, but always able to bite.
With a revised relationship between gearbox and engine management systems it could be fantastic.
FWIW I also agree with your thinking Peter, although possible not use of the Sport + button which amplifies throttle pedal sensitivity. In the days of early three speed auto transmissions the kickdown took considerable "thought" presumably as hydraulic pressures were built up and sent to the clutch bands. The effect, when it eventually happened, was a somewhat crude lurch forward with the dramatic reduction of engine to rear drive ratio. I remember a brief yelp from the skinny(ish) cross plies on my CV8 when the TorqueFlite gearbox kicked down to second and an even bigger one if you could persuade it to kickdown to first. The 460 lb-ft of torque from the Chrysler 383 were diluted by the delayed change, softish torque converter and sheer weight though.
Given nearly half a ton less, turbo torque on demand and dramatically quick changes of the Plus Six's fantastic ZF 8HP box its not difficult to see what it would be like on a slippery road to the unaware. Lack of LSD might help in the dry, spinning away excess power but things could go badly wrong in the wet before that could happen. To me there is something inherently wrong in deliberately not spec'ing an LSD on a car with this weight and power delivery to offset lack of traction control.
