Adam Opel AG (Opel) is a German automobile company founded by Adam Opel in 1862. Opel has been building automobiles since 1899, and became an Aktiengesellschaft in 1929. The company is headquartered in Rüsselsheim, Hesse, Germany. It became a majority-stake subsidiary of the American General Motors Corporation in 1929 and has been a wholly owned subsidiary since 1931.

Opel operates 11 vehicle, powertrain, and component plants and four development and test centers in seven countries, and employs around 37,000 people, with more than 20,000 of them in Germany as of December 2012.

Opel VIN decode

Digit 1-3 World Manufacturer Code (WMI)
WOL Adam Opel AG v Vauxhall Motors Ltd.
SCC Lotus
WJR Irmscher
VSX GM Spain
4GD GM USA
Digit 4 Wildcard/Special Model Identifier
Digit 5-7 — Model
91, 92 — Corsa A (2 doors)
93, 94 — Corsa A (3 door)
96, 97 — Corsa A (4-doors)
90, 99 — Corsa A (5 doors)
71 — Corsa (Combo)
33 — Kadett E “base” (3-door / tailgate)
34 — Kadett E “base” (4-doors / tailgate)
35 — Kadett E “base” (3-door / wagon)
36 — Kadett E “base” (5-door / wagon)
37 — Kadett E “base” (3-door / van)
38 — Kadett E “base” (Combo)
39 — Kadett E “base” (4-door / Sedan)
43 — Kadett E “luxury” (3-door / tailgate)
44 — Kadett E “luxury” (5-door / tailgate)
45 — Kadett E “luxury” (3-door / wagon)
46 — Kadett E “luxury” (5-door / wagon)
47 — Kadett E (3-door / van)
48 — Kadett E “luxury” (3-door / van-special)
49 — Kadett E “luxury” (4-door / Sedan)
51 — Astra F “GL” (5-door / wagon)
52 — Astra F “GLS” (5-door / wagon)
53 — Astra F “GL” (2 doors / tailgate)
54 — Astra F GSi (2 doors / tailgate)
55 — Astra F “GL” (3-door / van)
56 — Astra F “GL” (4-door / Sedan)
57 — Astra F “GLS” (4-door / Sedan)
58 — Astra F “GL” (4-doors / tailgate)
59 — Astra F “GLS” (4-doors / tailgate)
53-B — Astra F “GL” (2-door Convertible)
81, 88 — Ascona C (2 doors)
86, 87 — Ascona C (4 doors)
84, 89 — Ascona C (5 doors)
86 — Vectra A “CB” (4-door / Sedan)
87 — Vectra A “GL” (4-door / Sedan)
88 — Vectra A “CB” (4-doors / tailgate)
89 — Vectra A “GL” (4-doors / tailgate)
36, 19 — Vectra B (4-door / Sedan)
38, 68 — Vectra B (4-door / hatchback)
31, 35 — Vectra B (4-door / wagon)
53, 58 — Manta B
75 — Tigra
85 — Calibra
11 — Rekord E “base” (2 doors)
16 — Rekord E “base” (4 doors)
17 — Rekord E “luxury” (4 doors)
18 — Rekord E “luxury” (2 doors)
Digit 5-7 — Model
64 — Rekord E “base” (Caravan 2-door)
65 — Rekord E (vans)
66 — Rekord E “base” (Caravan 4-door)
67 — Rekord E “luxury” (Caravan 4-door)
14 — Commodore C (2 doors)
19 — Commodore C (4-doors)
21 — Senator A
29 — Senator A CD
21 — Monza A
22 — Monza A
29 — Senator B
25 — Diplomat B
26 — Kaptain B
27 — Admiral B
A6 — Sintra
16 — Omega A “LS” (4-door)
17 — Omega A “GL” (4-door)
66 — Omega A “CB” (Caravan)
67 — Omega A “GL” (Caravan)
19 — Omega A 3000 (4 doors)
21 — Omega B “GL” (Caravan)
22 — Omega B “CD” (Caravan)
23 — Omega B “STC” (Caravan, MV6)
25 — Omega B “GL” (4-door)
26 — Omega B “CD” (4 doors)
27 — Omega B “STC” (sedan, MV6)
A — Astra H, Zafira B
A — Agila A, Speedster, Tigra A
B — Corsa B, Combo B, Vectra B, Omega B
C — Corsa C, Vectra C
E — Speedster
E — component of body shape
F — GL (only Omega B), otherwise part of the body shape
F — Astra F
G — Astra G, Zafira
G — Astra G, Zafira
H — Agila
J — Vectra B
M — Astra F
M — CD (Omega B), otherwise part of the body shape
P — MV6 (only Omega B), otherwise part of the body shape
R — part of body shape
S — CorsaB, Combo B, Tigra A
T — Astra G, Zafira A
V — Omega B
X — Corsa C, Combo C, Combo C Van, Meriva, Tigra B
Z — Vectra C, Signum
Digit 8-9 — Body Shape
06 — Combination 4-door
07 — Coupe 2 door
08 — Limousine 2 door, hatchback
19 — 4-door sedan, 6 window sedan
25 — special delivery
35 — Combination 4-door
48 — Limousine 4-door, 4 windows, hatchback
67 — 2-door convertible
68 — 4-door sedan, 6-window fastback
69 — Limousine 4-door, 4 windows, step-back
70 — 2-door van
75 — Combination 4-door, special
97 — 2-door Targa
Digit 10 — Year
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
Digit 11 — Factory of Manufacture
1 — Rüsselsheim
2 — Bochum
3 — Azambuja (Portugal)
4 — Zaragoza (Spain)
5 — Antwerp (Plant II)
6 — Antwerp (Plant I) to about September 1992
6 — Eisenach from about September 1992
7 — Luton
8 — Ellesmere Port
9 — Uusikaupunki
A — Azambuja
B — Bertone, Turin
C — Eisenach
D — Doraville
E — Ellesmere Port
H — Hellas
S — Szentgotthard (Hungary)
T — Dunstable
V — Luton
X — Ellesmere Port
Y — Luton
Z — Izmir, TorbaliStellen
Digit 12-17 — Sequential Serial Number

Opel Automotive in the United States

Opel cars appeared under their own name in the U.S. from 1958 to 1975, when they were sold through Buick dealers as captive imports. The best-selling Opel models in the U.S. were the 1964 to 1972 Opel Kadett, the 1971 to 1975 Opel Manta, and the now-classic 1968 to 1973 Opel GT. (The name “Opel” was also applied from 1976 to 1980 on vehicles manufactured by Isuzu (similar to the “Isuzu I-mark”), but mechanically those were entirely different cars). However, there are and have been many cars sold in the U.S. that are based on Opel models or on platforms developed by Opel:

Buick Regal (5th generation, since 2009)
The Buick Regal is a rebadged Opel Insignia. The main differences are the modified radiator grill and the altered color of the passenger compartment illumination (blue instead of red). The Regal GS is comparable to the Insignia OPC. It was first assembled alongside the Insignia at the Opel plant in Rüsselsheim, Germany. Since the first quarter of 2011, it is now being built on the flexible assembly line at the GM plant in Oshawa, Canada.

Buick Encore
The Buick Encore is the Buick version of the Opel Mokka, developed by Opel in Rüsselsheim, but built in South Korea.

Buick Verano
This is the sedan version of the Opel Astra J, which appeared first in China as Buick Excelle GT, and is offered by Opel as fourth body form of the Astra.

Buick LaCrosse
Other than the vehicles listed above, the Buick LaCrosse is no rebadged version of an Opel model. However, it is based on a long wheelbase version of the Opel-developed Epsilon II-platform and therefore shares many key components with the Opel Insignia and thereby the Buick Regal.

Saturn Astra (2008–2009)
The Astra H was sold in the U.S. as the Saturn Astra for model years 2008 and 2009.

Saturn Aura (2008–2009)
The Saturn Aura was, especially in the interior, a quite heavily modified version of the Opel Vectra C.

Saturn Vue (2nd generation, 2008–2010)
The Antara was sold in the U.S. and Canada as the Saturn Vue for model years 2008 and 2010.

Cadillac Catera (1997–2001)
The Opel Omega B was sold in the U.S. as the Cadillac Catera.

Opel Auto background info source:
wikipedia.org