[msej449]

My UK Adaptive + High beam assist Xenons work as follows at night, when the ≡A switch is set and the ≡A button on the stalk is pressed.

After a short while with no other traffic ahead, the separate passenger and driver side full beam headlights engage.

If you drive into a well-lit area they both disengage, and the standard beam flattens a bit to illuminate the driver side pavement, to better highlight pedestrians and cyclists.

In the full dark and with both high beams engaged via ≡A:

On a straight road, if an oncoming car approaches, it creates an unilluminated 'box' around the oncoming car by spreading the high beams to the left/right for as long as possible. Eventually, it drops the driver's side full beam but leaves the passenger side full beam fully operating. This is particularly useful driving cross-country, where the edge of the road may not be very clear.

If a car appears ahead, it will create an unilluminated 'box' around the tail lights. This box will move up/down and left/right as the vehicle ahead moves vertically and horizontally. If you get nearer, it will eventually drop the high beams.

On a curve, it will drop the passenger high beam if it detects oncoming vehicles in the line of sight, so as not to dazzle them. But it will still 'box' the oncoming car as above, until it has to drop the driver's side high beam.

All of the above things happen concurrently.

The Xenon HBA+Adaptive has different physical assemblies for left-hand drive and right-hand drive cars. So when I drive to the Alps, I can't use the ≡A button in France and Switzerland and just have to use manual standard or full (left+right) high beam. This Xenon assembly is different in a non-optioned car, so you can't just enable Adaptive with coding - the physical baffles and lenses just aren't there.

My understanding is that in the USA, BMW either fits Adaptive assemblies but disables the control software, or doesn't fit the Adaptive assemblies at all. It isn't clear which applies to what models, and whether some models have a mix of the two approaches. That some people can retro-fit Adaptive simply by re-coding, while others are adamant they've been unsuccessful using the same coding implies the latter. The switch to LED also complicates the discussion, because in the UK certainly, some of the earlier LED headlights that were fitted definitively did not have an Adaptive capability although it seems that later versions do.

So what it looks like US customers will be getting is the full repertoire of functionality: Beam spread when entering well-lit areas; separate left/right full beams; separate full beam illumination of the passenger side at the same time as standard beam only on the driver side; dynamic 'boxing' of oncoming vehicles; dynamic 'boxing' of vehicles in front of you; and directional illumination.

There seems to be a separate landscape for directional lighting (on Xenons) i.e. where turning the wheel produces additional lighting in the direction of travel. Directional lighting seems to use foglamps and/or adaptive i.e. foglamps only where no adaptive is fitted, adaptive where there are no foglamps (as in the M-Lites), or both where both are fitted. However, I'm happy to be corrected on this and again, I've not got experience with LEDs, so they may implement this differently.

I also have a theory that the original BMW design engineers never envisaged adaptive and HBA as a separate option. They thought that all headlights would have all the necessary mechanical components to support the functionality of HBA plus adaptive. And it was only later that the marketing geniuses thought of optioning these two things, to increase revenues. So as a result, the standard beam is by default set lower than you would otherwise like it because the assumption is that it's only used when you're close to a car ahead (otherwise, the HBA/Adaptive woud be doing its thing). In addition, it caused a lot of annoyance in the UK because dealers didn't always make it clear that you had to order both, separately - quite a few owners complained that they ordered HBA thinking it gave them all the functionality of Adaptive as well, then found the car was delivered without Adaptive (i.e. the left+right high beams would both drop when it saw tail ights or oncoming headlights, but that's it). And in the UK, it got even more confused when people with the early versions of LED would fully-spec all the options and then find that they'd lost the Adaptive capability they'd got used to on their previous Xenon-based BMWs.

Finally, for those of you who haven't seen this technology - it works. I had HBA+Adaptive on my previous 3 Series as this made me choose it again for my current M235i. The 'boxing' tech really is impressive. But the HBA is not really any faster to respond than a human, which some owners find annoying and not up to expectations. Moreover, HBA can never match a driver who uses a cross-country road regularly and knows that, say, a twinkle along a hedge up ahead means a car will materialise 'round a corner suddenly, and would drop the high beam in anticipation. Notwithstanding such criticisms, I still think it's a great technology and I for one have never been flashed by oncoming cars while using it. One thing that you do need to get used to is that the headlighting can become sort of busy with all that boxing of oncoming and ahead vehicles on a busy road with a lot of curves. So I do still sometimes turn it off again on stretches where there's lots of traffic, I know the road well, the edges are very clear and all that high beam dropping/lifting and boxing gets distracting.