I have owned a Audi A6 4.2 Quattro, E350 Mercedes Benz, but the A8L 4.0T is by far the most spectacular car out of the three. The car is efficient, extremely stylish and the performance is unparalled to any of the cars I have driven. The 740i has nothing on this car. The S550 is stylish, but sluggish compared to the A8L. The E350 is absolutely a bore compared to the dynamics of the A8L. I wouldn't trade this car for the world. An extended warranty was cheap and assures me the stability that I want when I buy a supreme used car. Do yourself a favor and check this car out. I promise you won't be dissatisfied.