Unless you are a BMW (or Euro car) Master Mechanic and has the know-how and high tech tools to work on them (even then not many will want to own such a car to work on their weekends), we don’t recommend buying German vehicles, only lease them.  The thing about German vehicles people keep forgetting about is it’s not just the powertrain you need to focus on but all the electronics on board.  Did you know some German vehicles have over 100 computer modules on board?!  It’s a matter of time before they act up or go haywire on you, and then good luck getting it fixed - for complex problems you will have to take to a special shop that works on those vehicles or the dealer and they will charge an arm and a leg.  The smart way to own those modern complex German vehicles is to lease them under warranty.  That way if anything breaks, it’s on BMW’s dime.

Good powertrain with a smooth inline 6 and good transmission, but be prepared to spend a fortune in repairing and maintaining that thing. 

You already bought it. Hopefully you got some sort of extended warranty just in case. 

I drove the n52 engine and got it up to 200K miles. It’s the predecessor to the n55, and extremely similar.  Amazing engine. Biggest problem was the PCV valve going out, and the DISA valve going out, because they are made of cheap ass plastic.

They core of the engine is good. My gripe with it is it costs an arm and a leg to maintain. 

2013 335i means you have an N55 engine... Inline 6 with twin scroll turbo charge. Its the 2-3rd most reliable engine in BMW line up, has been around for 10+ years in almost all fully loaded BMWs. Common issues are, water pump might go out after 120k km, charge pipe (the plastic tube going to the intake on the drivers side) is made of plastic and usually after 100k km it might break. Valve cover engine might leak so check it once in a while, easy to spot if it is. Oil filter housing tends to leaks after 80-100k km. easy to spot if it is.other than that the only major catastrophic issue is that the first N55s had issues with rod bearings going out but is not a rule and have been revised in post 1st edition models like the 2013. Overall it is a good engine. and small components around it might fail but is not a rule. You don't need high end tools to fix it, just some specific ones that any store will have. there are plenty of YouTube videos about fixing most of those issues. N55 is common to go beyond 200k km.just make sure to change the oil no more than 5k km.. like 5000km or sooner. check sparks once in a while

2013 335i means you have an N55 engine... Inline 6 with twin scroll turbo charge. Its the 2-3rd most reliable engine in BMW line up, has been around for 10+ years in almost all fully loaded BMWs. Common issues are, water pump might go out after 120k km, charge pipe (the plastic tube going to the intake on the drivers side) is made of plastic and usually after 100k km it might break. Valve cover engine might leak so check it once in a while, easy to spot if it is. Oil filter housing tends to leaks after 80-100k km. easy to spot if it is.other than that the only major catastrophic issue is that the first N55s had issues with rod bearings going out but is not a rule and have been revised in post 1st edition models like the 2013. Overall it is a good engine. and small components around it might fail but is not a rule. You don't need high end tools to fix it, just some specific ones that any store will have. there are plenty of YouTube videos about fixing most of those issues. N55 is common to go beyond 200k km.just make sure to change the oil no more than 5k km.. like 5000km or sooner. check sparks once in a while