Thanks guys for all you input. My logic behind taking a serious look at doing it would be to simplify an amazing SUV by going with an engine that has tons of upgrade-ability in terms of tuning and performance and replacement parts aren't so expensive needing specialty tools to replace parts. The E53 X5, in my opinion, is the perfect sized SUV. The newer X5s are bigger and heavier so they came out with an X3 which is, in my opinion, too small. Enter the X4, but it's a slant back and crazy expensive. Electronically, the X5 is a nightmare to work on with WAY too many sensors and crap that isn't necessary. The engine is decent, for it's time, but you can't program it for highway mileage or turn around and quickly upload a more 'spirited' program for city driving, which the LS swap would be able to easily accomplish. The upgrades on the LS3 are limitless with stock hp of 420hp, cam'd 480+hp and then supercharging it will easily reach 700hp all day, everyday without the worry of cratering. E53 X5s are getting less expensive so factoring a conversion into the purchase of another X5 makes the next 10+yrs of driving a dependable vehicle very affordable. I have an 03 4.6is and I love it. I only have 140,000kms on it but the reality of it is that it's about to turn 13yrs old. I've already replaced the transmission ($5,500) and just did the timing chain and guides ($5,700) along with seals and whatever else needed doing at the time. It's now at the shop because the computer isn't able to communicate with the transmission for some unknown reason. Maybe I love the vehicle to my fault, but when I look around at other SUVs, and the thought of getting into payments on something newer while not really getting much for mine after all I've spent on it, it's really becoming clear why I still drive it. It's not for the re-sale value because they aren't a collector. We drive them because they're awesome and still look sexy as hell. Now just imagine not having to worry about anything mechanically and electronically the gremlins would be minimized. A buddy of mine did an LS3 swap into his E36 328 and it's a track monster. Another buddy of mine just completed an LS swap into his Infinity G35 and a Porsche Carrera as unreal as that sounds!! These engines have become the go to engine for classic muscle cars also and they're not getting any less popular.

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If you can still see the disapointment on his face in your rear view mirror, he's not far enough behind.
98 M3 Sedan blk/blk Sold
00 BMW 540i Sold
03 BMW 4.6IS
98 BMW E36 M3 modified