I think they would have an easier time meeting CAFE numbers with an LS as cylinder de-activation is more trivial with the pushrod design and more balanced in a 8cyl-4cyl design vs a 6cyl-3cyl design. Although, that being said, Honda seems to have figured it out in the van and V6 accord. I would love to see a DI, LS engine with Cyl Deactivation as a CTS option. 4.8 L with 350HP on 87 octane? Another $1000 option? Heck GM would make money on that since it has to be cheaper to assemble than the HF V6 with DI.