[bake]

In my opinion, the 535i is the safest bet as the car ages in terms of reliability. BMW is known for their silky smooth inline 6 cylinder powerplants. Of the engine variants offered on the F10 5 series, it appears the N55 in the 535 is the one with the least issues. Hopefully you will be fine with your N20. If you can afford it and planning on holding onto the car for a while, an extended warranty isn't a bad idea. Or you can do like me and just set that warranty money aside in case you need it for repairs. Always a gamble, but I was willing to take that chance with my N55.