Ya - we replaced my 4.6is with a new Mazda CX9, and it's nowhere near as fun or nice to drive as the 8 year old X5 was. I do miss it. But our situation changed and my wife is now driving the SUV daily during the school year so between that and family hauling on the weekends we are just logging too many miles to keep the 4.6is - just the consumables are quite expensive - tires, brakes, gas, etc. Got more than 20% of the original MSRP for it when I sold it too with 130K miles on it! I would not expect to see that with the Mazda. But even so, total ownership costs will be much lower - especially considering the purchase price is less than half to start with so right off the bat depreciation will be lower no matter what. That said, I bought the X5 used and way down on the depr curve so that cost was very low in my 2 years of ownership.

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2003 4.6is - SOLD
2003 M5 Imola
2008 Mini Cooper S
2011 Mazda CX9