Just to chime in with what most similarly cursed folks are saying about the
bizarre mortality rate of headlights that burn out on a4's. Sucker eats
them like candy.
Mine is an 2000 a4/1.8t
Once a headlight burned out in my car I seemed to be replacing the opposing
headlight every 3000 miles. I replace the left and the right burns out
quickly. I replace that right one, and the left gacks quickly.
I followed the advice of folks here and I can say that when I REPLACED THEM
BOTH AT THE SAME TIME (for reasons still unexplained) the car lasted over
15,000 miles before needing a replaced headlamp, and my lights are on *all*
the time (full blast, I don't have the Canadian "running lights" option).
Hope this chime-in helps. Just do them both at once.
PS. Because I'm clinically paranoid, I'm going to save up the living bulbs
and try installing them both at a much later date. Stretching my
imagination as to how that would help, but it's often good to rule out
superstition. Perhaps having equally "hurt" living bulbs in both sides
would equalize some analog circuitry, or something similar.