This SUV is poised at speed and well ... than speedy and luxurious enough, with the RS8 costing an extra $38,600—just shy of ...

On a pure power basis, the big Audi has been outclassed. A BMW X7 M60i brings 523 horses to the party; Mercedes-AMG's mild-hybrid GLS 63 SUV offers a frankly ridiculous 603 hp. That said ...