VH56 makes 420HP with 5.6L, gets 17/25mpg in a 4028lb sedan
Nissan VK engine - Wikipedia, the free encyclopedia
(Recent tech, 2010 Nissan Patrol, 2011 Infiniti M56)

LS3 makes 426HP with 6.2L, gets 16/25mpg in a 3875lb coupe
Chevrolet Camaro (fifth generation) - Wikipedia, the free encyclopedia
(recent tech, 2010 Camaro)

Pretty close if you ask me.

HP/L is roughly proportional to volumetric efficiency, which is influenced by head/valvetrain design. Cool from an engineering standpoint, but you're probably right - end users probably don't care.