2005 AWD Family Wagons Drivetrains

Can the oldest vehicle here really be the one that does it all? The Volvo XC70 has been around, evolving and changing names, since 2001. Volvo wagons, while suburban cliches, are highly regarded for good reason: They do the job they were designed to do better than anything else. The XC70 is efficient, quiet, comfortable--and it has no problem whisking you and your family away from the suburban sprawl, rain, snow, or shine. Johnny-come-lately AWD wagon/utilities may offer a different look and so escape the uncool-1960s stigma; they're all derivatives of the one that arguably started it all. The Volvo XC70 proves the modern family wagon has come almost full circle.

What's The Diff?
From a simple all-wheel-drive applique to a complex drivetrain, the four AWD systems here are fundamentally different. The Dodge Magnum utilizes a planetary gear set to apportion the power delivery 38 percent to the front and 62 percent to the rear. This front/rear split never varies and gives the Magnum the feel of a rear-drive car--most of the time. The Magnum SXT AWD can claw its way through understeer (under wide-open throttle) to a quicker average speed through the cones by pulling the nose where the steering wheel is pointed.

The Cadillac SRX AWD uses three "open" differentials (center, front, and rear) to allow the engine's power to vacillate from the normal 50-percent-front/50-percent-rear operation through gear pressures. The problem with this system is that it's easy to stymie. If a wheel begins to spin (when unweighted or on a slippery surface), its rotation must be checked by a braking force to stop futile spinning. This traction-control-based system essentially converts the engine's power to heat in the brakes when it can't be used to drive a wheel. Thus, the Cadillac can get itself out of slippery situations, but has no way of routing more power to the wheels with the most grip until it loses grip. It's a purely reactive system at its limit, not proactive. In the case of our slalom test (conducted with all stability systems off), understeer occurred at the limit of the vehicle that the AWD system couldn't overcome because the front wheels weren't spinning, but skidding.