Tire Tread/belt problems of the 2004 Nissan Murano

Gas mileage as stated on vehicle window sticker grossly exaggerated when compared to actual mileage. Car also had 243 miles on odometer at delivery. When questioned about this the dealer stated that the car was a swapped vehicle that came from a dealer in massachusetts. I was never informed of the amount of mileage on the car until I looked at the odometer upon pick up. There are over 240 miles on this car that are most crucial in the break in of an engine. I do not know how this car was driven during those miles and suspect that it may have not been driven with the care that I would have. I have placed several complaints regarding fuel mileage with both Nissan USA and biener Nissan. To date I have not gotten any resolution to this problem. I also had to replace both rear tires of this vehicle at approximately 500 miles. Both rear tires were progressively balding from the center line of the tire to the inside shoulder of each tire, to the point where the radial belt was exposed at points of the shoulder. The dealer explained that the dot numbers did not match with the front tires and that someone had switched them in. This also shows that the dealer didn't do a complete safety inspection on the vehicle before delivery.