Unless I am missing something the cruise performance in the SR20A POH is meaningless. For example, cruising at 12,000 feet and 55% power:
The Cruise Performance chart shows 145 KTAS at 9.5 GPH using best power lean. The Range / Endurance Profile for 12,000 feet at 55% shows 145 KTAS at 8.4 GPH using best economy. How can the best economy lean yield the same KTAS as the best power? Even if you accept that figure the endurance is given as 4.69 hours which I multiply by 145 and come up with 680 not 792 shown on the chart. The only way I can come up with 792 is if I use the best power KTAS with the best economy GPH and land with the tank empty.