[aerohead]

Half-bedcover : General Motors holds a patent for a half-tonneau,which covers the back half of a pickup bed,and demonstrates lower drag than a full tonneau cover.If combined with a cab extender which tapers in as it projects rearward,with about a 12-degree incline at top,and 7-degree at sides,you get about 20% drag reduction and 10% fuel savings at 55-mph,12% at 70mph.Any of that exposed underbelly that can be shielded from the on-coming air will yield dividends at the pump.