With the 2007 X5 3.0si, BMW carries on with an engine that countless fans have come to associate with the brand – the inline six. In this case, it's a 24-valve, dual overhead cam engine composed of magnesium and aluminum and featuring variable-valve timing. The use of relatively light materials helped engineers shave 22 pounds versus the 3.0-liter engine used in the 2006 X5, and also provided for marginal fuel economy gains (EPA-rated 17 mpg city, 23 mpg highway). Horsepower has jumped from 2006's 225 to 260 for 2007, achieved at 6,600 rpm. Torque has also increased, measuring 225 lb.-ft. at 2,750 rpm versus last year's 214 lb.-ft. at 3,500 rpm. Last year's six-speed manual transmission, a rare treat for enthusiasts in a segment almost completely dominated by automatics, has been dropped for 2007, as has the five-speed automatic. The only available transmission this year is a six-speed Steptronic automatic, which features regular, manual, and sport modes, though paddle shifters are absent. As with the BMW 7 Series and various products from the likes of Mercedes-Benz, the X5's shifter isn't moved down through the gears in a traditional way. Instead, it's a drive-by-wire system, with slight clicks of the knob serving to electronically change gears. It takes some getting used to, and seems like another possible case of technology for the sake of technology.

Fit under the X5 4.8i's hood is a 32-valve, dual overhead cam V8 with variable-valve timing that pushes 350 horsepower at 6,300 rpm and 350 lb.-ft. of torque at 3,400 rpm. EPA-rated fuel economy measures 15 mpg in the city and 21 mpg on the highway (during our evaluation we recorded 14 mpg). The 315-horsepower 4.4-liter V8 offered for 2006 has been dropped, and the six-speed Steptronic automatic is the sole transmission, which has been designed to provide quicker shifts and works with the drive-by-wire throttle to lessen lag.

Regardless of which X5 referenced, you're talking about a quick machine. BMW estimates a 7.8-second 0-60 mph run for the 3.0si, and a very respectable 6.4 seconds for the 4.8i, with top speeds maxing out at 130 and 150 mph, respectively. Not bad for a rig that tows up to 6,000 pounds and weighs about two and a half tons. That portly figure is part of the reason the X5 wears capable disc brakes (larger and vented for 2007) which are upsized about 15mm for the 4.8i. They're backed by ABS, electronic brake distribution and brake assistance systems, as well as all of BMW's leading edge brake technology – cornering brake control, brake fade compensation, brake standby, and brake drying.

BMW engineers are obviously focused on braking and acceleration, but they've also spent plenty of time on the 2007 X5's ride and handling. All versions benefit from xDrive all-wheel drive, traction control, hill descent control, and BMW's Dynamic Stability Control system (DSC-X). Hardware includes a speed-sensitive rack-and-pinion steering assembly, 18-inch alloy wheels rolling on 255/55 run-flat tires, an all-new double-wishbone front suspension, and a multi-link rear setup including coils on the 3.0si and air springs on the 4.8i with its automatic load-leveling suspension.

Available, though not standard hardware includes Active Steering and AdaptiveDrive. Active Steering is an electronic system that gives responsive steering a whole new meaning. When ordered without this technology, the X5 driver may need to rotate the steering wheel a full turn to get the intended result; with Active Steering, the response is more direct, meaning the wheel must be turned just a fraction of the original distance elicit the same result. As speeds top 55 mph, when too much steering input could be hazardous, the system becomes less direct. Similarly, AdaptiveDrive, operated by a button next to the shifter, gauges current driving conditions and adjusts stabilizer bars and shock stiffness as necessary.