Generation matters more than mileage with this compact. The 2011-2015 models earned their troubled reputation through a cascade of PCV valve failures that pressurize the crankcase and blow oil past every seal in reach, valve covers, timing covers, turbo lines all start weeping, turning ownership into a parts-replacement cycle. Coolant systems corrode from the inside out when neglected, and by 100k miles repair bills often exceed resale value. The 2016-2019 redesign fixed most of these gremlins and delivers the comfortable, well-equipped compact GM should have built from the start, but those improved cars are scarce on used lots. Manual transmissions of any year hold up better than automatics. If you're shopping used, a 2017 with 80k miles is a safer bet than a 2013 with 50k, the generation gap is that wide. Skip the first-gen unless you enjoy wrenching or have a trusted mechanic on speed dial.
Two generations, two completely different stories. The 2007-2018 Altimas earned their brutal street reputation with CVT transmissions that failed around 100k miles even with proper maintenance, steering column locks that stranded owners in parking lots for $900, and dashboards that melted in the sun while Nissan looked the other way. The 2019+ redesign fixed the catastrophic mechanical issues and added segment-rare AWD, but arrives so damaged by its predecessors that resale value craters and nobody trusts the nameplate. Nissan's decade of subprime financing flooded roads with neglected examples driven into the ground, turning 'Altima driver' into a cultural punchline that obscures the current car's actual competence. Pre-2007 models with the VQ V6 and traditional automatics are legitimately durable. Anything 2007-2018 is a transmission time bomb. The 2019+ is a rational midsize sedan at a discount, but you're buying a car everyone assumes is terrible, plan on keeping it forever because resale is punishing.