let's debate regular unleaded vs. premium (NON-MB)

[Will_w202]

I bought a 2008 Rabbit 2dr/5spd as an urban driver, since I didn't want to beat up my Benz with 17 inch wheels, 45 series rubber and Bilstein HDs around town (correction - it was beating ME up!) I test-drove one on a whim and was blown away with how solid and competent the little bunny is. Anyway, some of the kids over at the Rabbit site are debating grades of gas, and other than increased detergents in some prem fuels, I have pretty much laughed at them for running 93 all the time ( I run Shell V-power every 4th tank simply for the detergent properties - this is also what I run in the Benz).

The car is designed for 87 octane. 2.5l 5cyl, 9.5:1 compression. HOWEVER, a VW tech pointed out the manual states "for maximum performance, use premium."

What gives?