I'm modelling a sub-d car at the moment too... a Porsche 959. I guess I should probably open a thread for it in the WIP forum. For my edges I used partial crease and just kept applying it until the edge was as sharp as I wanted. 2 applications was enough on most of the edges.
here's a pic
Take a glance at my <a href="https://forums.simplymaya.com/showthread.php?s=&threadid=9428"><b>Porsche 959</b></a> WIP