Thirty years ago, BMW entered the all-wheel-drive market with the remarkable 325iX. Today, one out of every three BMWs sold in the world comes with the BMW xDrive all-wheel-drive system. BMW's success is not only a result of sales of its popular X vehicles, but also by xDrive-equipped sedans and coupes across all series.
Since the first BMW 325i “Allrad” was introduced at the Frankfurt Motor Show in 1985, BMW has built all-wheel drive into 1, 2, 3, 4, 5, 6, and 7 Series cars. The latest expression of all-wheel drive includes BMW xDrive in combination with plug-in hybrid vehicles. In fact, more than 110 models in twelve different BMW model series have all-wheel drive, not counting the BMW i8 plug-in hybrid sports car and BMW 225xe with electrified all-wheel drive.
To the untrained eye, the 325i Allrad looked like any other E30, so it was not until the automotive journalists had the opportunity to drive the car on a test track that they discovered, “The new BMW is the new champion when it comes to handling,” as reported by the German car magazine Auto Zeitung.
In 1985, the Allrad’s full-time all-wheel-drive system sent 37 percent of the drive power to the front wheels and 63 percent to the rears. Visco locks in the transfer case and rear differential created a rigid connection betwwen the front and rear wheels, thereby improving traction and stability.
In 1988, BMW changed the Allrad’s name to the BMW 325iX. Ever since, the “X” in a BMW’s name has meant all-wheel drive.
The next all-wheel drive model arrived in 1991, and it was the 525iX. On this car, for the first time, BMW controlled the all-wheel drive system electronically rather than mechanically. The 525iX came in sedan and touring versions, but BMW only built 9,366 of this E34 variant.
To retain the typical—and expected—feel of a rear-wheel drive car, BMW all-wheel drive systems send more power to the rear than the front. Drivers can feel it in the better and more precise steering response, more so than typical all-wheel drive systems offered by other carmakers—even German ones.
BMW took all-wheel drive to a whole other level in 1999 when it released the BMW X5, its first Sports Activity Vehicle (SAV). A planetary gear system split the drive power in a 38 to 62 percent ratio, while electronic control systems such as Dynamic Stability Control (DSC), Automatic Differential Brake (ADB-X), and Hill Descent Control (HDC) provided sporty driving on paved roads and confident traversing of off-road conditions.
The BMW X3 came along in 2003 and with it, BMW’s first generation xDrive all-wheel drive system. Was it any good? The team that used it to win the 2004 Alcan 5000 winter rally thought so. xDrive was based on a fast-acting electronic multi-plate clutch in the transfer case. It worked with the Dynamic Stability Control system to continuously adapt the drive power split to the current situation, making BMW xDrive the world’s first, and BMW says still the only, “intelligent” all-wheel-drive system.
After the X3, the xDrive all-wheel drive system was designed into the BMW X4 and X4 Sports Activity Coupe, as well as second- and third-generation X5s. Even BMW M got into the act, when an M-tuned BMW xDrive system, including Dynamic Performance Control, was installed on the ultra-high-performance BMW X5 M and X6 M.
The most recent X vehicle, the X1, showed up in 2009 and remained for years the sole occupant of the premium compact sport utility—make that sports activity— segment.
Not all BMW customers wanted X vehicles, but a great many wanted all-wheel drive, so BMW gave them what they wanted. The BMW 7 Series received xDrive in 2009, followed by the BMW 6 Series Coupe and Convertible in 2012, and in 2013, BMW offered xDrive versions of the Convertible, Coupe, and Gran Coupe 4 Series. The first 3 Series after the 325iX received all-wheel drive first in 2000. Technically, the first 5 Series with all-wheel drive came out in 1991 with the 525iX, but an xDrive 5 Series didn’t arrive until 2005. The 1 Series was annointed in 2012 and the 2 Series got it just this year.
The BMW i8 plug-in hybrid’s totally different powertrain layout precluded xDrive, so BMW engineers figured a way to have all-wheel drive by the electric motor powering the front wheels, the gasoline engine powering the rears, and the computer making everything work together.
BMW’s next plug-in hybrid will mate BMW eDrive to BMW xDrive. The BMW X5 xDrive40e will have the ideal combination of all-wheel drive to go anywhere and the power source to go there on electric or gasoline or both.
The clear advantages of increased traction and safer handling will make the xDrive and other all-wheel drive systems attractive for a large percentage of BMW buyers. Customers must be serious about it, because they will pay extra and as long as they do, BMW will keep making them. Since it involves BMW and technology, we’re pretty sure BMW's all-wheel drive will keep getting better.—Scott Blazey
[Photos courtesy of BMW AG.]
