All images courtesy of BMW of North America.
In the northern part of the country, you’d be hard pressed to find any luxury car that is not equipped with all-wheel drive today, save for a few GTs or coupes – though more and more of those have the four-wheel traction option than seems right. But that wasn’t always the case.
Just a few years after Audi transformed the idea of what people thought about four-wheel drive vehicles, BMW, too, arrived on the scene with an all-wheel drive 3 Series. At the Frankfurt Auto Show in the Fall of 1985, BMW introduced the 325i Allrad concept, an all-wheel-drive-equipped version of that seemingly ubiquitous small sedan that defined the company in the Eighties. Production soon followed in 1986, the Allrad name dropped in favor of 325iX.
That first full-time all-wheel drive system featured the same 171-hp engine found in the standard 325i (a model not released in the U.S. until 1987, where it was rated at 168 hp when fitted with a catalyst), but with a slick mechanical all-wheel drive system.
The 325iX featured two viscous limited-slip couplings, one at the transmission to split the torque front and rear and the other at the rear differential. In normal driving, the torque split was fixed at 37 percent front to 63 percent rear. With silicone as the viscous fluid, the coupling used multiple holed and slotted plates connected to each of the front and rear driveshafts. If the rear driveshaft spun faster than the first, the heat and friction would make the silicone more viscous, locking the coupling and sending more power to the front. Depending on available traction, up to 90% of torque could be diverted to one axle or the other.
Physically, BMW distinguished the iX from the standard 325 with a notably higher ride height, slight flaring to the fenders and the installation of a lower body molding kit. Introduced for Europe in 1986, American availability followed for the 1988 model year, but only in coupe format until 1989. All 325iX’s imported to the U.S. from 1988 through 1991 were shod with 15-inch wheels, at a time when 14s were standard issue on most two-wheel drive 3 Series models. Though never imported to the U.S. in any form, a wagon model, “Touring” in BMW-speak, also made the cut to get the all-wheel drive system.
With a roughly 145-pound weight penalty over the comparable rear-wheel drive model, the 325iX was not significantly slower, but all-weather traction improved dramatically. In no time at all, it seemed, the 325iX became the “official” car of the Colorado ski set. Today, like most E30 3 Series BMWs made in the Eighties and early Nineties, the 325iX has its own cult following, the cars long ago achieving collector status.
Though BMW did not produce an all-wheel-drive version of the subsequent 3 Series produced from 1991 through 1999, they did add a 5 Series to the mix in 1991 and it was the first all-wheel-drive BMW to include electronic controls in the all-wheel drive system. By 1999, the X5, BMW’s first SUV (Sport Activity Vehicle, or SAV in BMW-speak) was added to the mix. Produced exclusively in BMW’s South Carolina plant, that first-generation X5 had no two-wheel-drive option at all.
As more and more standalone X models arrived (X3, X6 and now X4), BMW’s stature as a producer or all-wheel-drive vehicles increased. As did their acronyms as the all-wheel drive system became increasingly electronically controlled and more sophisticated as they were integrated with the likes traction and stability control (DSC), automatic differential brake (ADB-X) and hill descent control (HDC). More recent models include torque vectoring on the rear axle that allows for additional torque split between the rear wheels, depending on which wheel has traction and which wheel needs it, a feature the company calls “dynamic performance control,” or DPC.
Just how pervasive is BMW’s all-wheel drive today? According the company, they offer xDrive (the name given to their various all-wheel-drive systems) on more than 110 models across 12 different vehicle ranges (including a few not sold here in the U.S.). To put that in perspective, BMW of the late Eighties had four model ranges (3, 5, 6 and 7 Series), with perhaps a dozen models in total available and all but the 325iX were rear-wheel drive only.
So, if you want a coupe, sedan, convertible, wagon, SUV, rakishly styled SUV inexplicably called a “coupe,” smaller SUV, smaller rakishly styled SUV also inexplicably called a “coupe,” a ridiculously powerful SUV, a ridiculously powerful rakishly styled SUV inexplicably called a “coupe,” or even a futuristic electric plug-in hybrid sports car from BMW with a sophisticated all-wheel drive system combining electric motors and an internal combustion engine, they’ve got you covered.
For purists, of course, there remains the original, the 325iX, with is cleverly engineered and relatively simple, purely mechanical all-wheel drive system.
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