It so happened that as I got to the restaurant of my choice yesterday the car park was full and so I decided I would make full use of Quattro to park by driving up onto a slope (about 12% steep) with only the two right wheels onto a grass fringe (wet with hail from a recent storm) while keeping the two left wheels on the road's tarmac. I was pretty confident Quattro would have no problem in driving up along the fringe for about 4 m so that the car was out of anyone's way. Well, I was totally disappointed to get a bitter taste of the old days when we used to get stuck without Quattro. Still refusing to believe this, I got out to check that there was enough clearance all the way up and there certainly was. Then I made sure the car did not nosedive into the fringe. Everything was OK but the car still refused to start off uphill. My only resort was to shily reverse onto the tarmac and try to find a more traditional parking space.
I was taken aback in such a way that on coming out of the family reunion meal I asked both my father in his A6 2.5TDI Q and my brother-in-law in his
02 A4 1.8T Q (on winter tyres) to try the experiment, as they were telling me it must have been a case of my EDL not working properly. Well, they got the same identic result: the front right and rear right wheels kept spinning to no avail while the other two did not move an inch.My conclusion is that while Torsen works flawlessly, EDL (Electronic Differential Lock) is no less than a big fiasco, at least when there is a big difference in terms of surface friction coeficient between the two sides of the car alongside.
I remember reading once that Jeep's Quadradrive and BMWs x systems had been the only ones to pass a certain traction test on rollers, while Quattro and the rest had failed, but I refused to believe this. Now I fail to understand why EDL does not work properly under those circumstances.
JP Roberts