My ‘06 was so-so reliability wise. The 4.4L V8 was a tank, absolutely no problems with it. The main thing that gave me issues was the air suspension system. My compressor died and had to be replaced, the height sensors gave out and had to be replaced, had to replace the bags at all corners. I also had the steering column lock failure, the steering column motor failed, the AC compressor failed, and other random electric gremlins (power locks randomly not working, sunroof randomly getting stuck, etc.). It was a joy to drive when everything was working properly and it never left me totally stranded. Ended up selling it and getting a Chevy Volt since I moved somewhere where a fill-up was $140. Still miss it sometimes.