My A3 has Bi-Xenon headlights and thus has DRLs (Daytime Running Lights) as well. I drive with mine switched on all the time. I have just returned from a holiday with my A3 in Austria and DRLs or dipped headlights are required by law to be used at all times in Austria and I personally found it certainly made seeing other vehicle at juctions etc very much better. The only cars not obeying the law on these lights were some 'foreign' cars that seem not to notice that everyone else had their lights on!
The use of DRLs is only 'advisory' in Germany but I would estimate that around 60-70% of vehicles were using them. In France the percentage was only around 20%.
To change my Bi-Xenons for use on the continent involved my dealer plugging in their VAG5051 computer and changing a setting. Whenever I turned the ignition on after that I had a 'beep' and a yellow warning symbol come up on the DIS to warn that the lights were set for left-hand drive. I have just been back to the dealer and they have set them back to normal and now no 'beep' or warning symbol.