well, i'm not the most knowledgeable it such things. but, since no one else has responded...
maybe no one has answered because there are many variables. so, my response will be very general and the standard disclaimer applies
absolutely moving to a car will help lower your fuel budget. but, your finances and the condition of your truck are not mentioned, so i have a few questions:
is your truck in good enough condition to sell?
can you afford to keep it JUST for hauling and buy a car as a daily driver, insuring both?
a hatchback or wagon might work. do you have a family requiring 4 doors?
the usual suspects have economy and reliability: honda civic, toyo corolla, even a ford escort or chevy/geo prizm(cheaper twin of the corolla). all come in 4 door and/or hatchback.
and by all means, research both here and the rest of the i-net.
hope that helps.