After spending the day sorting out the alignment on my Panda I thought I'd post this up in case anyone else contemplates it. I had searched the forum beforehand but didn't come up with a definitive answer.

It turns out that there is a good bit of fore and aft adjustment available in the brackets that connect the rear axle bushes to the body, simply by slackening the 3 bolts for each bracket, moving the brackets and doing the bolts back up.

It looks like the back axle on my car wasn't installed properly at the factory. Both back wheels had different toe settings from each other and so the overall thrust angle was off. After adjusting the brackets all is well, both sides have the same toe and the thrust angle is dead ahead.

Having said all that, the rear bushes seem quite soft and I wonder if the axle will make some small attempt to align itself when the car is moving, because if one wheel is toed in too much perhaps it will be forced backwards more than the other wheel.. :shrug: