Yesterday I challenged oppo to come up with the largest cylinder differentials offered on one particular model of car at any one time. The highest we came up with was a difference of 8 cylinders.
Yes, in 2011 you could get a 4-cylinder S250 CDI and a V12 S600.
From Ghost Dog:
Audi A8 (current Gen.) is available with a 2.0L 4 cylinder and a 6.3L W12. Does a hybrid count? Difference of 8 cylinders.
Can't believe I didn't think of this one earlier: late Cadillac V-16s (Series 90) were essentially altered versions of the Series 75's platform, which was a V8. That ties the S-class and Audi I4/V12 splits.
Finally from me, Yowen:
The Mercedes SLS, avaliable with 0 cylinders (electric) and a V8