<human>: Give me a shortened version of the text

This may be just USA, but Car Rental reps will ask you this question: Do you want to prepay for the gas? We charge so less than the normal gas prices..you can bring back empty...<< insert siren song>> 

I thought about this a little too much. In the end i decided to do a hypothetical study. If the local gas price is 2.48 (current lowest in my area) and hertz says you can buy a whole tank for 2.00 per gallon, should you go for it? For this study i assumed a full-size car -nissan altima which has got avg. 33 MPG for a city-highway mixed trip, and has an 18 gal gas tank. I checked the situation for different lengths of trip. from 200miles to 1000 miles. 

You can see my calculations on google sheet: 

Feel free to check and question my findings. I would like to know this too. 

From my calculations, it seems that if the number of miles drivable on a full tank of gas is less than your total miles to be driven, there is no financial point in prepaying for gas. So the more you need to drive, more sense it makes to buy that gas.

Caveats: 
1. You are returning to an airport and saving time on return trip is paramount.
2. If you are going to travel through some areas with much lesser gas prices as a norm, better gas from there when you return. (Gasbuddy is your buddy).
<bot>: In most cases, if you are driving more miles than a full tank will take you, prepay is a good option.