Harley-Davidson has been famously litigious over the use of its trademarks, most notably of all over the attempt to patent the 'potato-potato' exhaust note. This is a distinctive sound, a product of the 45-degree V-twin which because it's not produced by any other motorcycle is instantly recognizable as emanating from a Harley. The company reasoned that this too could be copied by a rival manufacturer and so began exploring whether it was legally possible to patent a noise, even one as distinctive as this. The legal process went on for several years and in 2000 an Australian musician by the name of Bill Cook was actually to claim that he'd taken out an American copyright on potato-potato when making an album called Steel Stallions in 1993. According to Cook, legal counsel for Harley-Davidson had been trying to reclaim ownership of the patent through the US Patent and Trademark Office, despite opposition from rival manufacturers. The musician cheekily maintained that he was prepared to hand the copyright over if Harley-Davidson gave away a copy of his album with every bike it sold, for which he would charge $15 a time. It's true that Harley-Davidson gave up its attempt to patent the sound in 2001, but was it really because of Cook? 'It's a nice story,' said one Harley-Davidson official, 'pity it's not true.'