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When my radio draws 90 watts, then I'll worry.
DRL circuits using the headlight filamants are powering what are normally 55 watt each electrical consumers. The reduced lumen output to about 80% of full power is the result of cutting the voltage at the lights by about 10% (wattage being reduced with the square of the cut in voltage.)
Your 110W lights are using about 90W in DRL mode.
But.... that reduction in voltage at the lamp socket is usually produced from a resistance wire that adds resistance, that is electrical consumption, too.
90 watts is about 1/8 of a hp (90/746). The alternator has to produce at minimum this amount of power to prevent battery depletion IF the conversion efficiency from mechanical to electrical is 100%.
At steady state speeds car x might require 12 hp to continue moving, no climbing, no accelerating, just to push air aside. That's enough for most to maintain 50~60 mph. The DRL are increasing fuel consumption by 10% to add that .12 hp they use. (correction: 1% of 12 hp)
At steady 30~45 mph when hp requirements for steady state operation might be 6 hp, those DRL are now adding 20% to the load. (correction: 2% of 6 hp)
DRL are useless in stop and go city driving. I know there's a car behind me. There are no passing areas where I need to alert the innatentive oncoming driver to not pull out to pass.
DRL are useless on divided highways. There are no oncoming vehicles. Closing rates of traffic approaching from behind leaves sufficient time for me to become aware of their presence long before their lights might be a notice of last resort.
DRL have a purpose in far northern (or southern) latitudes with long hours of dawn and dusk due to low sun angles, where sparsely settled, with long flat stretches of single lane road, providing opportunity for passing at high closing speed in proximity to oncoming traffic.
That doesn't happen where I live.
I don't run my wipers when it's sunny. I don't burn my headlights when it's sunny either.
However, There is a way to implement DRL sensibly (my definition of 'sensibly', anyway). The use of 5~10 watt dedicated bulbs can produce as identifiable a sign of presense of a vehicle as focused, high beams used as DRL.
I have just the setup RVanEngen mentions on the Camel II, but I havent wired up an equivalent on the Turdle yet (but its DRL are defeated).
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dosco 
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