If you have the dipped headlights on, then pushing the headlight lever away from you once brings up the white headlight symbol, which means that the main beam assist mode is active. If you push the headlight lever again, this activates the main beams, effectively over riding the auto headlights.In main beam assist mode, the main beam is activated provided the following conditions are satisfied1 The car is driving more than approx. 40mph, and2 There are no street lights within range3 The main beam assist detector has not identified cars coming towards you (via their headlights) or in front of you (via their tail lights)The theory re street lights is that by definition it is a built up area and that with the street lighting and limited speed, you would not need to use main beams. You can of course override this by pushing the headlight lever away from you to manually activate the main beam, and back towards you to go back to dipped beams.What this all means is that you need to be going above 40mph on a road without street lights and no car in front of you within range. I find the system then works very well. However, it is fair to day that under these circumstances, if there is intermittent traffic on the road there isn't much benefit in having main beam assist. Also, there is a slight lag of about a second or so between detecting that there is nothing in range, and activating main beam.In terms of this evening, if traffic is detected then the main beam won't come on.Let us know how you get on