I recently got in contact with an engineer who was (and still is) employed at Opel Motorsport at the time that the 4WD prototype was built (1982-83). He sadly couldn't give me more information but did gave out an interesting statement: the first prototype was a road car. He wasn't aware of the rally prototype as shown in the picture. However, this brings up interesting questions since the prototype seen in the press picture has similarities to both the road and rally versions.
In fact, when you look closely at the picture above, you can see that the car is equipped with a roll cage and that it does sport the squared arch extensions from Irmscher (as is the rally version). It also features the tall roof antennae (as is the rally version). However, it is equipped with the normal production hood (bonnet). The front bumper cover is different from both the road and rally version, it seems to be closer to the road version but with the lower air duct enlarged. The grille itself has only one horizontal slit instead of the two on the rally version. The auxiliary lamps are also placed differently than on the definitive rally version as well.
As such, I am trying to correctly identify some exterior features to fuel my suspicion that maybe the road car prototype mentioned was later converted into the rally version seen in the picture. From the information that I have, 245 road homologation cars of the rear wheel drive Manta B400 were produced but I have seen many differences in the exterior features. I know that the wide arch body kit was optional and fitted out of factory by Irmscher but that doesn't explain the other minutes differences. However, since I am not a Manta expert, can someone explain to me the differences between these:
In this picture the car sports grille with only one slit. The headlight washers nozzles (I assume it is what the little dots are) are on the inboard side of the turn signals. It also seems to sport some sort of black protection strips on the front bumper cover lip, side skirts, rear arches, and rear spoiler.
In this picture the car sports the same grille but the headlight washer nozzles are on the outboard side of the turn signals. The Opel logo is also different. This car is lacking the protection strips and also features a vinyl graphic on the rear part of the bonnet.
In this picture the car sports a two slit grille. The headlight washer nozzles are gone. The protection strips return. The bonnet is of the rally version. This car also has a sunroof and small antennae.
In this picture the car also has no headlight washer nozzles. The headlights themselves are different and with a mask (as is the rally version). The normal bonnet returns with the top graphic. The roof antennae is in the front instead of the rear on the sunroof car.
Now, were these simply different factory options? It seems odd to me that an homologation special produced in such little numbers could be custom ordered. Was the early homologation cars different? One other possibility is that some of these pictured above are not real B400 homologation specials?
I'm not sure why I'm going through all this trouble but I guess that the Group B nerd in me is fascinated with such details...
EDIT: I've just found some interesting details in the production run."The number of homologation vehicles produced in different years production is summarized below:
1981 - 23 units (before facelift)
1982 - 80 units (after facelift)
1983 - 140 units
1984 - 2 units"
This might explain a lot actually... Anyone can confirm which of the pictures above are PRE or AFTER facelift?