One of the great things about this blog is that we keep a pretty good inventory of rare cars written up, so that when one looks familiar we can go back and check it out. This doesn’t always work, as occasionally we forget that we’ve written one up, such as the S6 Avant I managed to write up twice. However, both of today’s tuner cars appeared on these pages before in one form or another, and I managed to track both down. Later we’ll look at an Alpina B11 3.5 that was seen here five years ago, but with 332 made it was still a bit surprising that the same one popped up for sale. When it came to today’s Ruf BTR Slantnose – one of only five made – I was sure we’d seen it before, and I was somewhat right…