low milage 10 or better X5M calls me daily. Right now with a wedding in 2 months its not feasible but sometime down the road.

Pfft....after owning so many BMW's - and surprisingly enjoying this sole venture into the SUV/SAV segment - I will likely end up with a Honda Accord coupe if I don't keep the X5 at the end of the lease. :D I keep teetering between the idea of keeping the X5 or getting the new M4 (..I love me some ///M cars), but the alternative idea of choosing a less expensive (..but fairly mature) vehicle is an admittedly attractive premise. I guess time will tell.

I thought the whole premise was to make the purchase of a new ride while you are single BEFORE you get married ha. That's what all my buddies say.

I just came to the same conclusion. I was planning on waiting for the F15 and when I saw the photos I traded my 2011 E70 for a 2013! This Is my 3rd x5 and 3rd E70! I love this car and the build quality gets better in each year of each generation.

how have M cars in general been to maintain beyond the 4 year mark? Much worse than the non-M versions? More can go wrong is seemingly a given, but are costs that much higher too?

Don't know about the turbo ///M vehicles specifically, but turbo versions of other brands that I have a history with, tend to be 2-3x in diagnostic & repair costs...

That said, sure wish I could stuff an X5M Engine under my 4.8i hood :thumbup:
The rest of my SAV is awesome, but the extra 200HP would make it perfect. Maybe someone will do an aftermarket turbo kit for the E70...??

This is tempting:
BMW : X5 Still Under in BMW | eBay Motors

HIGHLY doubtful! Hell, you can barely find software for a 35i. Unless you own a 5.0/X5M twin turbo, you're SOL.