Someone told me that all 8P A3's are now built in Ingolstadt, Germany? I'm not sure about 8L's but I assume it's one of the factories listed below.
Position 1-3: World Manufacturer Identifier
W = Germany - originally West Germany, hence the W
AU = Audi
All TTs (and only TTs) have this WMI instead:
T = Hungary
RU = Audi
Position 3-6: Filler digits (ZZZ)
Position 7-8: Audi Model Number - 8L for A3 1997-2003 8P for A3 2003 on
Position 9: Check Digit
Position 10: Year Code
A = 1980
B = 1981
C = 1982
D = 1983
E = 1984
F = 1985
G = 1986
H = 1987
J = 1988
K = 1989
L = 1990
M = 1991
N = 1992
P = 1993
R = 1994
S = 1995
T = 1996
V = 1997
W = 1998
X = 1999
Y = 2000
1 = 2001
2 = 2002
3 = 2003
4 = 2004
5 = 2005
6 = 2006
7 = 2007
8 = 2008
9 = 2009
Position 11: Plant Code
A = Ingolstadt
N = Neckarsulm
K = Rheine
T = Gyor, Hungary
Position 12-17: Serial Number
This is a sequential production number