I do own X5 4.8 but I am having so much trouble with this vehicle so I was wondering if Cayenne S is very reliable car that I don't have to go to dealership every week or every month to fix something.
How is porsche taking care of maintenance? such as oil change ore replacement of audio or little parts in cars?
what is their warranty?
What would be the good price for cayenne S?( how much over invoice?)

 

I think the more important question is what do you need? what will you be using your SUV for? mostly transferring people? 4WD? Towing?

I own a 2005 Porsche Cayenne Turbo, about 36K miles. I had my stereo system replaced recently under warranty. The single disc player would not play, but the 6-disc CD did. No other significant issues. A few people have mentioned electrical problems. The Cayenee warranty is a basic warranty, does not include oil changes like BMW, and I believe is 4 years/50K. The local dealership has been very good.

I previously owned a 2001 BMW X5 3.0. However, Ihad many electrical problems in my previous X5, including door locks and window operations. I also had a failed steering pump...all replaced under warranty. Nevertheless, I like the BMW X5, and the full warranty BMW offers isbest in its class(literally everything is covered!).
Additional strengths of the Cayenne include the following:
1) The Cayenne has locking differentials and can go offroad much easier than most of its competitiors, except Range Rover. In other words, it is an AWD system on the road but can be a fulltime 4WD system offroad. I take mine offroad occasionally, usually on fireroads in north Georgia. BMW X5 is NOT an offroad vehicle.
2) The Cayenne can tow 7700 lbs. I tow a trailer with my sports car that weighs together about 7000 lbs. Very few midsized SUVs can tow this much.
3) The Cayenne Turbo (optional with other models, including the S) has a pneumatic air ride height system that allows you to set a low setting on the road. As a result, the SUV rides better. Lower center of gravity, less body lean, you get the picture. It can also be raised up to almost a foot off the ground; lowest setting is around 6 inches for loading.
The Porsche Cayenne is an outstanding all-around SUV, but most buyers will not use its full potential (see above).

I would recommend checking out www.autotader.com and www.ebay.com for range in pricing for the Cayenne S.
Spend some time on the manufacturers websites for Porsche and BMW to learn more about these vehicles. Lots of reviews on www.caranddriver.com, www.roadandtrack.com, and www.motortrend.com.
Best of luck.