I also have no regrets in buying the diesel. I never owned one before and after test driving one against the 35i it was a no brainer for me. The 6sp tranny is not that big a deal with me and if gas mileage is your main concern than IMO you should by a smaller less bulky vehicle and not even be looking at an X anyway.

I have had one issue with mine in 15k+ miles (O2 sensor) and never had a DEF warning yet.

I'd buy one again if I had the need.

Enjoy whatever you choose

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2011 x5 35d - Delivery Feb 28, 2011
Platimun Gray/Oyster Nevada Leather; Dark Bamboo Wood Trim; Cold Weather Pkg; Premium Pkg; Premium Sound Pkg; Rear Climate Pkg; Technology Pkg; Comfort Access; Multi-Contour Seats; Heated Rear Seats; Head Up Display; Roof Rails; Space Saver Spare Tire

2011 Infiniti G37x
Premium Package; Navigation Package; Interior Accents

2009 335i xDrive (Gone but not forgotten)
Sapphire Black/Oyster Nevada Leather
Cold Weather, Comfort Access, Logic7, Navigation