Easily the most potent engine is in the Acura. It has 265 horsepower and is much quicker than the 230 horsepower Lexus and the M Class's 232. This comes at a price though as the Acura's overall gas mileage barely topped 17 mpg in mixed driving whereas the Lexus was frequently above 21. The Mercedes was the least fuel friendly, and it needed premium fuel, at 16 mpg, but it had the largest fuel tank and so they all had a highway range of about 400 miles. The weight of this vehicle obviously impacted gas mileage and performance. The Lexus was the lightest at just over two tons, while the Acura was about 500 pounds heavier and the robust Mercedes nearly 800 pounds more.
Off roading is was all Mercedes. The M Class has a transfer case, more sophisticated drive system, and an engine that produces more torque when needed. It also has decent control, tows more (5000 pounds), and has more ground clearance. It is obvious that Mercedes built this SUV with off roading in mind and perhaps, misjudged a buying public that was more interested in the idea of off roading rather than the actual journey. Thus sales have slowed considerable after an initial rush of orders. The Lexus has the least ground clearance, over an inch less than the M Class. The Acura, as usual in this case, finished in the middle with eight inches of height. As for a verdict, I would vote for the Lexus, especially considering the disappointing gas mileage for the Acura. You also should take into consideration that the Lexus has the newest design of these three and thus has a real advantage.
Young working woman's view: This isn't even a fair fight. The Lexus is my choice.
The Mercedes turning radius is much larger than the others, with the Lexus being the tidiest, but not that nimble, at 38 feet. Even inside it is all Lexus with more room and more comfort. The Acura has 82 cubic feet of storage with the backseat folded flat, the Lexus 85 and the Mercedes 81. The Acura and Lexus come with a third row option, but the MDX has more people room inside, abeit by just an inch or two because it is longer.
Driving-wise the MDX is easy to manage, while the higher Mercedes takes longer to adjust to, and to be honest, never seems to be luxurious. The Acura has more interior noise and the more complicated seat controls. All of the cars have excellent seating, but the dead pedal on the Acura is poorly placed and the parking brake release is way too difficult to manage if you are wearing a tight skirt. Speaking of which, the Lexus is easy to enter with a perfect slide in height. The Acura isn't that bad, but the Mercedes requires some serious effort. The Lexus and Acura rear seats fold flat, but the M Class has a slight incline. All of these luxury vehicles are masters at ease of operation. Everything is easy to open, slide, push, pull, tilt, and lift. Speaking of which, I did like the power rear hatch on the Lexus and would absolutely make it a must order on my option list.
As a businesswoman when you look at the features in each model you can quickly see the plan each manufacturer had for their SUV. The Lexus has a rear seat that offers 40-20-40 split bench verses the others 40-60 splits. This makes it much easier to take a family and still have room for skies or other long items and to separate fighting siblings. The Acura is the only one that does not have one-touch power windows on all the doors. Thus my verdict is that the Lexus and Acura were clearly designed with a full family in mind.