After all-numeric 7 digit plates reached 999 9999, the remainder of the Gnn nnnn series was issued, then Xnn nnnn, Ann nnnn, Hnn nnnn, Knn nnnn, Lnn nnnn, Nnn nnnn, Pnn nnnn, Rnn nnnn, Snn nnnn, Vnn nnnn, Enn nnnn, Ynn nnnn, and now Znn nnnn. It appears that after exhausting the E series, the last part of the Ynn nnnn series is being issued. The Y series was only issued through Y67 nnnn on the previous base, so the unused Y series numbers are now being issued on the current base.
Highs in order of prefix letter appearance:
G high - G98 0207
X high - X99 9936
A high - A99 7721
H high - H89 7160
K high - K99 8417
L high - L99 8688
N high - N99 9933
P high - P99 9967
R high - R99 9984
S high - S99 8541
V high - V99 7027
E high - E99 9411
Y high - Y99 2951
Although the C series is not known in this format, Gunther Frostyburger reports seeing C89 7813.
As with some other states, Illinois plate numbers are all over the place. Keith Foreman proves that point by informing us that he just received new plates for a new car in Feb. 2011 with the number K51 3190, yet he received K50 3791 in Oct. 2009 for another car.
Keith reports an unusual general issue number, 0111. Illinois does not generally issue a leading zero on any types other than State-Owned Trailer. Joey Hurd reports Illinois issues leading "0" for passenger dealer series and for the highly-coveted four-digit plates. They are available through connections to IL State Gov't.
Gunther Frostyburger reports T51 9581 and T 60 0169 on the new base. They were originally issued on the old base and were kept by the owner.
Keith Foreman spotted Z18 1263 on 2014-08-26, but no other Z series plates in this format have been seen. Keith also spotted Z30 641, which was obviously an older number, but it was on a new plate.
Gunther Frostyburger - 3 Apr ’19