Running my Merc on chip fat

Well, perhaps not chip fat - biofuel is about to break through the barrier and be acceptable to motorists. 5% of biofuel will be mixed in with 'ordinary' fuel, to help with the environment. According to the press, my Mercedes will be pootling along [at the legal speed limit] with the smell of popcorn coming out of its exhaust. If it helps the environment - bring it on...