The differential is centered in cars but the pinion is offset so the driveshaft is also offset to join the pinion. In many cars the drive shaft is long enough to allow that offset to be made up along the driveshaft with the u-joints. With Cobras short driveshaft the engine has to be slightly offset to align with the differential.
I understand that this is an older posting, but since it has been renewed by another today, so please permit me to comment.
If the O.E.M. wanted the engine centered in the chassis, and if it were the differentials' offset positioning due to if the diff. itself were centered, then the O.E.M. would just reverse the relationship to create a centered pinion receptacle; which they have done many times in the past. And there is no requirement for the differential to be "centered", and in many examples it is not as engineered by the O.E.M.'s.
There are many considerations for the placement of componentry in the chassis, and yes the engine and transmissions' centerline is generally preferred to be "somewhat" in alignment with the pinion shaft of the differential; but for example the universal joint manufacturer actually recommends that they "not" be in true alignment with one another. Rather they generally recommend something like a 1-1/2° to 3° minimum offset for a longer service life, this as to work the roller bearings, creating rotation within the caps and about the trunnion, this enhancing the movement of the lubricant and also reduces the tendency for particularly the trunnion to become "staked" by the rollers. Values in excess of say 5° to 7° starts to accelerate the heating and wear rate, though still acceptable, past 12° to 14° really is to avoided but often witnessed particularly in "Jacked-Up" 4 X 4's.
So why is the engine offset to the passenger side of many vehicles, not just Cobras?
Because it was decided a long time ago that along with perhaps needing the space in the foot-well for pedals & feet in operation, the owner, whom most often paid (paying
) for the vehicle, and most often drives the vehicle, the manufacturer is trying to make that person feel better about their choice by making it feel roomier for them, this at the expense of the passengers somewhat, but whom really rarely complain as even if they might feel even a bit cramped, it still sure beats walking!
Scott.