4.6 vs 4.4 2003
 

I'm also interested in buying a 4.4 or 4.6 v8.
Is so much the difference of pushing you in the seat when you start from a traffic light? I only try the 4.4 and it was very good in the first meter it is very agressive! I love it! What about the 4.6 in the first seconds?

i haven't driven any other model but my '03 4.6is and i must say it's pretty amazing the amount of power this thing has.

i took this from another website -

"According to BMW, the 3.0i automatic accelerates from 0 to 60 mph in a quick 8.6 seconds, the 4.4i in a very quick 7.4 seconds, and the 4.6is in a startling 6.5 seconds.

The performance of the 4.6is would be quick for a sports sedan. For an SUV, it's amazing. Its performance allows the 4.6is to compete comfortably against the Mercedes-Benz ML55 AMG. ML55 comes with an AMG-tuned V8 rated 342 horsepower and 376 pounds-feet of torque, giving the M-Class Mercedes nearly identical 0-60 performance. We doubt that many X5 owners will drag race their neighbors. But they will notice how the 4.6-liter V8 makes terrific sounds when they step hard on the gas. And how smooth, responsive, and quiet it is when driven around town."

Provided by: New Car Test Drive
Source: New Car Test Drive

Thank you, and what about fuel consumption?

well, it's obviously not the greatest and a lot will depend on ur style of driving. if ur constantly mashing it from light to light; obviously ur gas mileage will suffer. most of my driving is highway. recently on my way from DE to MD (approx. 100 mile trip), i averaged 18mpg at about 74mph.