I doubt whether anyone could withhold from smirking when Jakob Nielsen started bashing BMW's iDrive interface for the BMW 7-series. Somehow it's always interesting to see a renowned brand go face down with the usability of a high profile product. The New York Times also took a shot at iDrive in this 2002 article entitled Menus Behaving Badly:

In a lesser car, you might simply twist a knob. In the 745i, tuning the radio is an interactive experience at 75 m.p.h. After a bit of this, you may wonder what's the fuss over handheld cellphones.

If you want a small preview of the iDrive experience yourself, take a look at the iDrive instruction movie above. Personally, I had a hard time keeping track... I heard that BMW dealerships were actually giving courses to their customers on how to work the iDrive interface. User group properties might also come into play here: the average BMW 7-series owner might age between 45 and 55, and not be the most tech-savvy, mobile phone devouring user.

Another NY Times article - Driven to Distraction - points out what I believe to be a fundamental flaw of iDrive: using a screen and menu-based in interfaced in a usage situation (driving) that places a considerable cognitive load on the user. The wonderful thing of having 'hard' buttons on your dashboard is that you can use your 'muscular memory' to locate and operate a function.

Dialing up a particular radio station -- one of 700 functions iDrive controls -- requires almost all of these movements, as well as a fair amount of attention to a dashboard screen.

BMW is a company that is not particularly well known for intensive user involvement during product development. "BMW knows what's good for the customer," seems to be the company's mantra. In terms of cutting-edge technology and styling that might be true; the company does come up with high quality cars with a very distinctive form factor (that sometimes take some getting used to...). But I think that a user interface - especially a radically new and very important one - should always be thoroughly tested, and I can't imagine that this has happened on the first iDrive.

Of course, BMW is not the only car maker that's implementing a 'state of the art' interface. Audi has Audi MMI (multimedia interface), and Mercedes has COMAND (COckpit Management And Navigation Device, (how's that for an acronym!)). Wayne Cunningham from CNET reviews all three systems. So I guess this is the future, but I'm not sure we should go down this road. BMW disagrees and promotes its newest version of iDrive with the slogan "maximum usability, minimum complexity". They've got guts, those Germans.

More uselog posts about iDrive
> More BMW iDrive Reviews: The Evoluation of a Bad Idea
> BMW iDrive Version 4.0 Promises Improved Usability
> Study: Usability Evaluation of Multifunctional Systems in Vehicles