Comparing two cars via their lifetime price
The first thing I would try is so factor out the input-prompting routines:

 private static Scanner input = new Scanner(System.in);

 private static int askInt(String prompt) {
     System.out.println(prompt);
     return input.nextInt();
 }

 private static double askDouble(String prompt) {
     System.out.println(prompt);
     return input.nextDouble();
 }


In my opinion, there's no particular reason why the car price, fuel efficiency, or distance numbers should be integral.  Why not just do all of the work in doubles?

public class CarComparison {
     private static Scanner input = new Scanner(System.in);

     private static double ask(String prompt) {
         System.out.println(prompt);
         return input.nextDouble();
     }

     public static void main(String[] args) {
         double carOnePrice = ask("Enter the price of car one: ");
         double carTwoPrice = ask("Enter the price of car two: ");
         double gasPrice = ask("Enter the price of gas in your area: ");
         double carOneMpg = ask("What is the average mpg of car one? ");
         double carTwoMpg = ask("What is the average mpg of car two? ");
         double milesDriven = ask("Give me an amount of miles total you think you will drive in this car: ");

         double gasCostCarOne = (milesDriven / carOneMpg) * gasPrice;
         double totalCostCarOne = gasCostCarOne + carOnePrice;

         double gasCostCarTwo = (milesDriven / carTwoMpg) * gasPrice;
         double totalCostCarTwo = gasCostCarTwo + carTwoPrice;

         if (totalCostCarOne == totalCostCarTwo) {
             System.out.println("The two cars cost the same.");
         } else if (totalCostCarOne &lt; totalCostCarTwo) {
             System.out.println("Car One will, in total, cost less than car two. Buy it.");
         } else {
             System.out.println("Car two will, in total, cost less than car one. Buy it.");
         }
      }
}


For completeness, I've added handling for the unlikely case of a tie.

A next step might be to define a totalCost() function or to define a Car object, but I think that for this problem, the benefits of further changes would be marginal, and I would just leave it at that.