Originally Posted by mr.xpowerseller
I'd install little LED's inside of the low beam assemblies that are powered on when the ignition is on. It would look nice and be really cheap. The last thing you want to do is power on all the exterior lights all the time, as it would burn out the bulbs faster.
Well, this is what we do, have all lights (low beams) on all the time, day and night, summer and winter (not in the garage
). My 221 is approaching 4 years and all together I've changed one bulb from a W210, two W211 cars, W204 and W212 that we've had in the family and that was a trunk light bulb on the second day on one of the 211s.
I've had a lot older models (read "much older and quite a few of them") and have certainly changed bulbs but those were the good time in our memories, it hardly happens any more, at least not frequently.
Within EU we now have new DLR rules that allow LEDs like mr.xpowerseller seems to refer to. According to the new rules, those are sufficient and rear lights or low beams are not needed any more. This would be an option, also as an after market approach if allowed in OP's country, is it Canada?
Is it not sufficient if you activate DLRs from the cluster menu or does the SLK not have that? Perhaps country specific version coding would activate permanent DLRs?