Ford started this nonsense in '66 with the addition of the Galaxie 500 7 Liter (428 cubes). They were heavily involved in international motorsports at the time, and were running the 427 (again, 7 liters) in the Ford GT Mk IV (they actually called the 428 the 428 even though it was actually 427, so as not to confuse it with their race motor). As for Ford calling the 302 the 5 liter (the 'point- 0' is silent.), was for SCCA Trans- Am racing (even though the engine is 55 cc's shy of 5,000), they just rounded up, as their big 6 for the trucks was, at 300 cubes, a 4.9.