Usually the model code is one letter followed by one or two digits. This second digit might be to identify the car body type:
0 = 3 doors
1 = 5 doors
2 = SW/Station Wagon
3 = 4 doors
4 = Crossover/SUV
5 = Coupe
6 = CC/Cabrio Coupe
7 = Cabrio
8 = Monospace
9 = Utility
For instance, the Peugeot 508 II (R8) might be the saloon version (R83) or the station wagon version (R82).
Recent models code:
S3 = iOn
S1/S2 = 106
B0 = 107
B3 = 108
A0 (A08) = 1007
M24 = 205
T1 = 206
T3 = 206+
A7 = 207
A9 = 208
P21 = 208 II
A94 = 2008
P24 = 2008 II
M33 = 301
C28 = 309
N3/N5 = 306
T5/T6 = 307
T7 = 308
T75 = RCZ (308 Coupe)
T9 = 308 II
P5 = 308 III
T84 = 3008
P84 = 3008 II
D6/D7 = 405
D8/D9 = 406
D2 = 407
T73/T93 = 408 (3-box 308, Asian market)
I3 = 4007
J3 = 4008
W2 = 508
R8 = 508 II
T87 = 5008
P87 = 5008 II
Z6/Z7 = 605
Z8/Z9 = 607
U60 = 806
V2 = 807
MCVU/MCVF = Bipper/Tepee
X2/U5/U9 = Boxer
M49-59/B9 = Partner
U64/U65 = Expert I
G9/K0 = Expert II