HP appeals to the uninformed emotion. It must be better if it has more power. I especially love "I can't safely merge on the highway without a v6".
Stupidity all around.
Doesn't mean big engines are bad, or high power vehicles are bad. But there is an emotional attribute that is used as an objective comparator ("this number is bigger than this one), that sells. Even to people desiring to buy appliance cars. Precisely why you get V6 Camry and similar vehicles.
Cars have gotten bigger, and heavier, and engine tech has improved to the point where recent v6 sedans get the same kind of mileage as last-gen 4 cyl.
But I do wonder what an optimized reduced power 4 cyl vehicle could do.
Pretty sure my accord hybrid is a reasonable example. It would get 40 mpg no matter what, even without the hybrid function. I mean, city driving... traffic, lots of idling, going nowhere fast. This is based upon my experiences forcing engine ops for winter heat.
But that sort of thing only appeals to peoples' pocketbooks when fuel kicks their butts. The rest of the time, the power number sells.