Gas Mileage Issues

i'm not sure my guages don't work right atm but i know a 17 mile trip to my cousins house one way will eat up a quarter tank and back home it'll eat the rest up 30 dollar fill ups are killin when my van will get me 40 miles to a major town and 40 miles back and only eat up a quarter the whole time.

it's a 225 ci slant six 1barrel carb all original and numbers matching with the car itself. so making it cooler under the hood should help out things a bit or no?