Well there were some minor updates to the 06 but I would't say that the 06's were more reliable. I have a 05 6 with the I4 4 speed. I run it somewhat hard at times and I have not had any major trouble. I had a alignment issue when I first bought it. But the engine and transmission are running like new. I use AMS oil btw.

 

There were more changes made between 05 & 06 with the V6 model than with the I4 from what I understand. Exhaust routing was changed, suspension geometry was changed and a couple other things were revised between those years in addition to the obvious changes in body styling.