UPDATED: MINI’s All4 System and “100% Power to the Rear Wheels”

[UPDATE] We’ve reached out to our sources at MINI and received clarification on BMW’s announcement last week concerning what appeared to be an update to the ALL4 system. We reported on BMW’s description of the system sending 100% of the power to the rear wheels. However, we also expressed skepticism that perhaps this was an example of MINI and BMW having trouble consistently communicating the details of this system. Our sources are telling us that in actual fact, it’s a little of both.

So let’s clear this up. The ALL4 system can split power 50/50 between the front and rear wheels. It can also put 100% of power to the front wheels. In the case of no traction to the front wheels, it can send all of its available power to the rear wheels, but MINI is saying explicitly that this is still only 50% of the car’s total power. So what BMW described is, in a sense, correct (in that the car will be RWD for that instant); but the chosen language did not account for this nuance.

Descriptions notwithstanding, MINI has also confirmed explicitly that the ALL4 system has not changed for 2013. It’s the same system the Countryman shipped with in 2010. I repeat, it has not been updated. This post, on the other hand, now has.

Original story after the jump.

MINI’s all wheel drive system, known as All4, was introduced in 2010 with the launch of the MINI Countryman. This was MINI’s first foray into AWD and it, along with the Countryman’s four doors, have catapulted the R60 to signifiant sales success. The system was originally described as an extra weapon in the arsenal of MINI’s Dynamic Stability Control (DSC) traction control system. The Countryman would default to FWD and add power to the rear wheels as necessary, up to 50% of engine output. While not a performance-oriented system, MINI All4 quickly proved itself as a significant traction aid, especially on snow. MINI has recently released updated information on the system and there’s something in there we think MINI fans are really going to like.

Before we get into that, let’s quickly rewind to December of 2011, where we got to sit down with Heinz Krusche, the head engineer for BMW’s Driving Dynamics devision. Our seats happened to be the front buckets of the JCW Countryman prototype. While flying around snowy alpine roads, Heinz described the All4 system for us anew, and his description had some very interesting differences from how MINI and MINI USA had been describing the system. Heinz told us that the All4 system actually starts as a full-time 50/50 power distribution front to rear. Then as needed, up to 100% of the power is diverted to the front wheels. This can happen for traction needs, or as straight-line speed increases (the system goes 100% FWD at speeds above 80 mph).

Today BMW Group released information regarding both BMW xDrive and MINI’s All4 system. New models in the BMW lineup, like the 1 series, will now be available with xDrive for the first time. That’s of little interest to most MINI fans, but where things do get interesting is in their updated description of the All4 system:

The system is based on an electromagnetic centre differential and distributes drive force at continuously variable levels between the front and rear axle. In normal situations on the road, up to 50 per cent of the drive torque is directed to the rear axle – in extreme situations such as when driving on ice or snow this figure can go up to 100 per cent.

There are two key points to take away from that paragraph. First, the power distribution front-to-rear is now being described as “continuously variable” rather than FWD first, as it was originally described by MINI USA. This terminology seems much more inline with our information from the Countryman event in Austria last year. It’s unclear if the system is still defaulting to 50/50 from the gate, but one thing is beyond dispute: the All4 system is putting power to all four wheels at all times.

The second key point from the BMW press release has to do with front-to-back power distribution. For the first time, the MINI All4 system is being described with 100% of available power being diverted to the rear wheels in extreme traction situations. Our most recent information had 100% of power available to the front, but only 50% available to the rear. Did BMW decide that if All4 is really about traction that a RWD bias was the better formula? Or has MINI once again failed to get its story straight in describing the system?

Unchanged is the All4’s relationship to DSC. The All4 system is not described as a performance-oriented system intended to go toe-to-toe with the Subaru WRX STi on dry pavement. Instead, MINI says it’s designed to work hand-in-hand with the traction control system to give the best possible traction on slippery surfaces — something that both Gabe and I can attest to, having driven MINI Countryman All4s extensively on snow in Minneapolis, Chicago, and the Alps. Yet, while MINI doesn’t publicly describe the All4 system as a performance option, they obviously think it’s adding something. The All4 system is standard on both the JCW Countryman and the JCW Paceman.

What do you think? Does a RWD bias change how you think about the All4 system?

  • would be nice if it was selectable, giving the ability to engage RWD as a preference. Presumably it’s just an electronic switch therfore programmable?

    • les

      I second that.

    • BimmerFile_Michael

      The issue at hand, and why the system only uses RWD 100% in extreme bursts, is that the system in current form was not intended to be RWD. There would need to be some component changes to make that possible for longer periods of time.

  • So is this a physical change to upcoming ALL4 systems, or a software driven model that will apply to older/existing once downloaded?

    • Presuming what they’ve given us is accurate, this would be a software change. The front-to-rear differential is electronically controlled and the rear section of the system was already engineered to deliver up to 600 ft-lbs of torque.

      • Henry

        I remember prior to ordering ours in Sept ’10, reading an article describing the All4 system, that under hard acceleration the power to the rear wheels would be 100%. Not sure what happened between that and the release of the R60 to the public.

  • that.guy

    Default F/R bias is what really matters in terms of dry surface performance, imo. If they are still starting with 50/50, then this does not mean they have tuned it to an RWD bias. Make the default 40/60 and then we can talk…

    • You are correct. When I said bias, I meant in terms of where the car goes looking for traction. Previously it went toward the front wheels, now it goes to the rears.

      • that.guy

        Only if the fronts got nuffin.

  • hi how r u

    So, I have an S ALL4 2011 built. Do i have Access to the 100% rwd? Do I have to go in for a software update? Or is it actually a new differential changed? thanks

    • Perhaps. Although I’m not personally convinced that MINI hasn’t simply (yet again) failed to accurately describe how the system works.

  • Don Hopings

    Related, but a bit off topic: I wonder what the WRC cars got? Fulltime 50/50 or a variable system more along the lines of the street car?

    • The WRC cars got a bespoke system developed by ProDrive.

      • Don Hopings

        Yes, but is is a constant split or does it vary? Many years ago, ABS was tried in F-1. Drivers didn’t like it because you had no control over it. You activated it by pressing the brake pedal and the system did what it was going to do. I would think there could be a similar issue to having an AWD system that moved the torque around perhaps not to the driver’s liking in a given situation.

        • I don’t know how it splits the power for the WRC cars. I’d imagine it was wheel-by-wheel, but I don’t know.

  • This article is misleading

        At no time will the current ALL4 system ever be able to send more than 50 percent of the power to the rear wheels. The MINI ALL4 system has a mechanical split of power at the center differential with zero torque biasing capabilities  This means that the only way the ALL4 system can vary which axle gets power is with the All4 clutch. The problem is that by the time the ALL4 gets power it's already been cut in half. Even with the ALL4 completely locked it's still a 50/50 split.

        The only way to send power over 50% to the rear is to remove power from the front. With the exception of traction just not being there (ice, snow, wet) this is impossible. The power from front wheels to crank are mechanically linked with zero clutching. This means that conditions pending, the front wheels will always receive at least half of the engine torque

    • As I say in the article, I’m skeptical that MINI is describing the system correctly. We’re attempting to confirm with our sources, but for now that’s what MINI is saying.

      • Thank you. I am a huge fan of this site and I have a lot of customers that quote it as reference. I just don’t want them steered in the wrong direction.

        • To be clear I was very skeptical of this as it was the exact same language they used in the original press release when the car was introduced. At that time I questioned the engineers about it and they confirmed quickly that the press release was incorrect in how it was described. I assumed the same thing was happening here but until we had confirmation we didn’t know for sure. As you see in the update to the article, we now have confirmation that it was indeed incorrect.

  • lavardera

    On a different note, I think the steel wheels on that Paceman look cool.