Is it bad structure if u access a class via another class. For example
class engine{
car.specificationclass.printme()
}

would it be better if I passed the pointer instead?
specificationclass.printme

with that small amount of code it is really hard to tell if it is a bad design or not. i may have a (useful?) comment if you provide some more context.

having one class inside another is a main principle in OOD, its called composition.

whether your doing it properly or not, is another question that i dont know the answer to.. as mentioned, theres very little code to analyze the situation.

are you trying to say 'an engine has a car'? at least thats what it looks like... you should have an engine object in the car class instead.
then again, i could be totally off, because im assuming this is what you want, but dont know because of the little code.

if this is an answer to your question, then good! if not, then please elaborate or give more code.. but dont overwhelm us with it.