15 mpg is great for 540 hp. Mileage also affected my purchasing an RHO over a gently used TRX.I will spend $90,000 by the time I put plates and some window tint on her. Who gives a shit about gas mileage at that point. Especially if it goes back to prices it was 4+ years ago, which I expect it might.
I don't get the MPG nitpicks - a 540 HP truck is not good for MPG, it's simple physics