I have an '04 Audi Allroad with pretty hard paint as well. I had good luck with my Flex using orange pad and Menz PowerGloss, followed by white pad and 106FA. There were still some lurkers there, but the PowerGloss worked pretty well. I have soem
M105 as well that I just picked up and will be giving it a whirl in next few weeks as well. To me, the PowerGloss works very similar to Menz IP in terms of workability and the Flex. Just has that little extra bite to it. If you're careful enough you can get PG to finish down LSP as well.