If you don't drive more than 5k a year it will be hard to justify adding another vehicle to the fleet, even if its given to you.
1) 5k miles a year is roughly 100 miles per day
2) rough #s, but let's say you average 15mpg in your truck and 30mpg in your new car, that's 6.7 gallons per week of gas used in the truck and 3.3 gallons per week in the car. Even if gas was $4 a gallon, that's less than $15 a week in savings. By the time you figure purchase price,title fees, registration, insurance,maintenance/repairs, and you'll never break even let alone get ahead.