Doesnt premium fuel burn more cleanly though?? Like more complete?
...only if the engine is optimized for it. There are no sensors to determine what octane rating is in the tank. Either way, you'll never make up the price gap.
However - as already mentioned, the price gap is a subjective worthwhile expenditure for those who prefer the cars that require it.
Let's also not forget that smaller displacement turbo engines are "purported" to use less fuel than their similarly-powered, higher cylinder count options. Fuel savings may make up for the turbo difference.
My mother's Lexus RX400h 'recommends' premium. Is there a basis for it? I'm still not sure. Sales guys will say yes, gearheads will say no, and one who follows the manufacturer's recommendations would say "yes, sir!" IMHO, when you buy (not lease) an expensive vehicle and plan to drive it into the ground, you follow what the manufacturer recommends.