Beer + Grapefruit Soda = Beer?

Eric:  Apparently it’s pretty popular, but I just had my first Stiegl Radler (Grapefruit) today.  They claim it’s half Stiegl Goldbrau, and half fruit soda.  It tasted exactly like Grapefruit Pelligrino, which I love, but I have trouble considering this a beer.  Especially at only 2.5%.  If I drank 10 of these, I’d be more…