If your current automobile needs new tires (estimate at $400 installed) and averages only 15 miles per gallon, how much (in addition to your trade-in value) can you afford to spend for a car averaging 30 mpg? You expect to drive 15,000 mile/year and expect gasoline to cost $4.00/gallon and you will keep he car 10 years. Your personal interest rate is 6%/year.