They're offset for steering box clearance. Typically unless you have a hole cut in the hood for a scoop and you have to offset the air pan to line everything up, most people will never notice the offset.
In all but the most restrictive, pure stock, circle track classes you are allowed some amount of offset and set back and drop. Any savvy car builder is going to relocate the entire engine and driveline to maximize their car to these rules, regardless of what the car was laid out with originally. One of the classes I ran in specified that engine set back would only allow the front most spark plugs to be in line with the upper ball joints, left side bias was limited to 55%, and the crank centerline could be no lower than 12" above the racing surface. With specs like that, you pretty much knew where everything had to sit in the car to meet the intent of the rule book.
Yeah, unfortuantly, I've trashed a few decent cars racing. That's why I switched to chevys and fords for a while. Let me tell ya, you learn to appreciate a lot of mopar traits while driving the other teams stuff.
