Do your own due diligence and find a good 35d. They are out there, but be willing to set aside some money for maintenance. As others have said, they are no different than other BMWs...

Most diesel parts on the 35d have extended warranties attached - 10 year, 120k mile. I recently picked one up with 94k miles on it. One-owner, limited service history but I made sure to thoroughly check over the vehicle. Immediately upon purchase I did EVERY fluid on the vehicle: brake, transmission, transfer case, differentials, motor oil, etc. Most of these items a beginner/novice DIYer can do.

Will the suspension need a refresh at some point? Obviously, all vehicles will
Will the cooling system need a refresh at some point? Obviously, all vehicles will

Don't rush into any vehicle, get a PPI done, ask for service history (physical hard copies), etc.

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2004 BMW M3 Individual
2009 BMW E70 X5 35d
2011 BMW E70 X5 35d - Totaled
2009 BMW M3 E90 - SOLD
2006 E53 X5 4.8iS - SOLD
2002 E46 M3 Convertible - SOLD
2006 E46 M3 ZCP - SOLD
2011 E70 X5 35d - SOLD
2000 E39 ///M5 - SOLD
2003 E53 X5 4.6iS - SOLD
2006 E83 X3 3.0i MSport - SOLD
2000 E46 323Ci - SOLD