Introduced by Nissan's Infiniti division in 2011, you would assume any inaugural bugs had been worked out by 2013, the QX's third model year. Power was supplied, in the press vernacular, by Nissan's proven 5.6-liter V8 producing 400 horsepower and 413 pound-feet of torque. A seven-speed automatic transmission was standard on all models, and while the additional speeds might suggest some semblance of efficiency, no one should confuse this big QX with a Toyota Prius.
Our 'for sale' example, with 84,000 miles, represents above-average mileage for a 4-year old vehicle. But if those are largely highway miles in and around Madison, Mississippi, and service records are available, you shouldn't be too concerned. This is, with proper maintenance, a 200,000-mile platform, leaving you about 116,000 miles for your $37,000. And the 'ask' seems about $5,000 too dear; perhaps the seller will throw in a gas card.