Use fog lamps as daytime running lamps?

Can someone tell me if this is allowed if you set the NS so strongly in the direction of the road that they can no longer blind the oncoming traffic. In my area is so rare fog that I never use the things as such. Day-time driving lights however quite, especially since I spare the expensive Xenon headlights and save electricity or petrol by the smaller wattage. Do you have to go to the TÜV if necessary? (design change and the whole Circus?) What happens if you tell me in a police control can: “It doesn’t dazzle anything and driving with the light is better than without?” Does anyone know a solution?