As you would expect, a major part of the iDrive interface is consumed by BMW's navigation system. For the most part, it's a pretty conventional solution for a built-in system. Both 2D top down and pseudo 3D map views are available, while traffic data is provided by the RDS-TMC system and is therefore several steps behind the likes of TomTom's HD traffic.
Conventional address input can be done with both the iDrive wheel and voice command. The latter does not require training and in our experience is extremely accurate. However, it's worth noting that like so many built-in navigation systems, post code input is limited to five digits, following which users must identify the relevant street from a list and add a house number. That's absolutely normal for this kind of system, but falls short of the full post code support of even cheapo aftermarket navigation devices.
As we mentioned before, the system supports split screen, allowing navigation cues to be retained throughout the iDrive interface. In terms of routing, three main options are offered: Fast, Efficient and Short, with each displayed on the map with mileages. Users can further tweak routes in the usual manner by choosing to avoid motorways, toll roads, ferries and all that jazz.
All of which is pretty predictable. What, then, marks out BMW's navigation system from the competition? We'll start with the good stuff. Arguably the best bit is the ability to send navigation data to the car remotely (see MyInfo in the Connected Drive section above). The system also deserves a thumbs up for overall quality of presentation as well as accuracy and reliability in terms of locating and tracking the car. For the most part, it's a great system to use - clear, precise and intuitive.
Predictably, it includes a points-of-interest database, too. As already noted, it's actually more reliable than the Google Search function in the ConnectedDrive system. But let's not get too carried away, it's very similar to systems offered by competing car manufacturers.
Despite all these strengths, the navigation system is not, however, perfect. For starters, the audible guidance notes are poorly paced. The first warning of a turn or exit is often given too soon and the final command sometimes a little too late. The net result of which is that you may forget about the first warning only to fall into something of panic when the final cue arrives abruptly. In our time with the car, the system also occasionally gave moderately inaccurate or misleading directional commands. In this regard both Lexus' in-car system and the likes of TomTom, to give just two examples, are clearly superior.
We're also a little underwhelmed by the 3D option in the navigation interface. Superifically, it's one of the best looking currently available. It appears to show proper terrain relief and even includes full 3D renderings of certain key points of interest (Salisbury cathedral being the best example during our tour of duty), which is fun even if the models are very low fidelity.
However, with use you realise that the relief shown on the map is cleverly faked - the system doesn't actually know the lay of the land, so to speak. More to the point, in 3D mode the system feels sluggish. Given the high resolution of the screen, this probably reflects hardware limitations. However, we've so far been unable to identify the hardware driving the interface. It's been announced that future BMWs will pack Intel Atom processors. But that won't happen until at least 2010.
A slick and easy to use Bluetooth interface is an essential tool for any road warrior and here the 330d scores highly. The synching process with our commodity-spec Motorola test handset was utterly fautless. The system quickly keyed into the contact database on the handset. Once synched, it's possible to select contacts using the voice command system. Just like the address input in the navigation system, we found voice command for contacts to be surprisingly accurate. Again, no training of the system is required for this feature, it just works.
The same goes for dialling telephone numbers via voice command. In fact, the system is quite capable of recognising full numbers spoken fluently using normal conversational diction. The sound quality of hands free calls through the system is also excellent from both ends - those we spoke to while on the move said background noise at their end was well suppressed. Another nice little feature is the network signal strength indicator that remains visible through most of the iDrive interface.