Well, I did it again.
I blew a heater hose a few weeks ago, which I suspect also caused a leak in my head gasket, which has caused me to lose coolant every day (seems to mostly blow out the reservoir, due to overpressure). To stem my coolant losses, I've tried to keep my speed below 65 (under 65, I only lose 6-10oz per 50miles; at 70+, I'll lose 30oz or more). As a consequence of this granny-driving, I've been getting mid-60s mpg.
Last time I hit 900, I was P+G'ing. This time, I mostly used cruise control to keep my speed down. As I neared 900, I did more drafting and P+G to stretch it out. I was going to chicken out and fill up at 895, but I was confident I could eke it out one last trip... and... I did! The final results:
948.1 miles, 15.03 gallons, 63.1mpg
Avg speed= 53.1mph, Coasted 260.5mi
At 0 mph: 0.14gal, 01:17 (hh:mm)
1-29mph: 1.14gal, 42.9mi, 37.7mpg
30-39mph: 0.75gal, 50.5mi, 66.9mpg
40-49mph: 0.78gal, 58.7mi, 75.7mpg
50-59mph: 1.48gal, 115.3mi, 78.0mpg
60-69mph: 9.12gal, 598.5mi, 65.6mpg
70-79mph: 1.55gal, 81.1mi, 52.3mpg
80+mph: 0.02gal, 0.9mi, 50.48mpg
I was late for work on one or two days, so I had to push my speed higher than desired. Also, I hadn't figured out the speed/coolant connection until 200miles into the tank, so if I knew then what I know now... Well, I've now got half a mind to try for 1000. All I need is to bump 63mpg to 66.6.
I poured in a spare gallon when it was all over, and I had to crank a couple times to restart the engine, so now I'm pretty, pretty, pretty sure that 15.0 gallons is my max capacity.