Update: Currently 750 miles on bugs Camry. MFD shows 51.6 mpg. I estimate the following gallons used based on subtraction of:

2 from 51.6= 49.6 mpg = 15.12 gallons used. Should hit 800 miles on a tank of gas with 16.2 gallons used.

3 from 51.6=48.6 mpg = 15.43 gallons used. Should hit 800 miles on a tank of gas with
16.5 gallons used.

4 from 51.6= 47.6 mpg = 15.75 gallons used. Should hit 800 miles on a tank of gas with 16.7 gallons used.

Since the bugs has been around 50+ mpg for as long as I can remember on this tank...I believe I will use 16.2 gallons used with 1 gallon to spare. I'm confident and going for the 800+ run.