Nothing.
I came from a BMW 540/six speed and after a very short relationship with an Infiniti G35 coupe, I realized that the two door lacked convenience and the Japanese interior was did not fit with the overall mission of the car.
I got back into a four door, eight cylinder German car with a six speed and, this time, with all wheel drive. I was comfortable and much more satisfied with the "experience" although at a substantially higher price.
It is a bit smaller than my BMW and the overall handling is a bit less refined, but the engine is a wonder and, so far, nothing has fallen off or quit working.
"This is a very fast and agile gas guzzler that meets all of my needs"
What gas mileage does it get?
The mileage is about the same on both my Explorer and S4. Approximately 17 mpg mix city/highway. City driving only expect 13-14 mpg max.
Just wanted to add the comment that the tires that came stock with this 2004 model are very prone to slow leaks. I've had issues with all 4 of mine over the past three years.
Although it is not a huge deal to take somewhere and get the leak plugged I thought it was worth mentioning here because it happens so often.
They are Continental 235/40 ZR18. Otherwise the tires themselves feel great on dry pavement when fully inflated.
I purchased some caps that turn red when the tires are not fully inflated to 40psi.