Our test session's major surprise isn't that the X5 trumps all in braking and handling. It's that the BMW doesn't sweep the acceleration tests as well. Despite a class-leading 425 pound-feet of torque, the X5 is soundly beaten to 60 mph by the smooth-whirring RX 450h. The whopping 0.3-second disparity seems supported by that tenet of drag-racing mathematics-100 pounds is worth a tenth of a second-but weight can't be the only issue. Yes, the BMW outweighs the Lexus by just over 300 pounds, but the ML320 weighs 40 pounds less than the X5 and finishes last, 1.7 seconds behind the Lexus. Little mysteries like these swirl in our heads as we trek north on Highway 395.

For all their differences, one thing these lux trucks have in common is the sensory recalibration they require during the first few minutes of driving. Though their sumptuous tuning means neck-snapping launches are kept to a minimum, lead-footing any of the diesels unleashes a veritable tsunami of low-rpm torque.

The X5 elicits the most grins, but not just from its precision-weighted steering and road-hugging dynamics. St. Antoine can't get enough of its "ocean-liner" torque. "Cruising up the 395 grade out of Bishop, the X5 never even downshifted-just kept grunting away as we stormed up to 8000 feet. Altitude? What altitude?"

The VW impresses for different reasons. "Definitely has a softer suspension and does like to lean in corners, but once used to the motion, taking a set and throttling through corners becomes a blast," says our colleague and off-road expert Mark Williams. While patters of diesel vibration can be induced from both the Benz and BMW, VW engineers have somehow managed to quash nearly all oil-burning shudders. "Very plush, composed ride, much quieter than the BMW's," says senior editor Ron Kiino. Our editors also note the Touareg's spry response off the line, no mean feat for a beast approaching 5400 pounds. "Almost responds like a V-8 gas engine, without the usual engine lag after you punch the gas," says Williams.

The oddest bit is how all the diesels feel quicker than the Lexus. "Wait a second, which one was faster at the track?" blurts St. Antoine over the radio, incredulous at how quickly the BMW pulls away from the Lexus on our road loop.

Perhaps a rolling-start advantage? Williams doesn't think so. "At 7500 feet, these diesels still feel strong and powerful while delivering 20-plus mpg. Not bad for 5000-plus-pound SUVs. The much lighter Lexus with much cooler technology gets hammered in the cold and altitude."