3. Driving too much car
Certified financial planner Mari Adam has seen couples with car payments totaling $1,400 a month. Would it kill them, she wonders, to drive cars that combined would cost them closer to $800 or $900?
Another planner, Chris Cooper, has suggested as a rule of thumb that you don't spend more than 8 percent of your monthly gross income on a car payment, less if you have credit card debt.
Money Magazine has estimated that driving less expensive cars could yield an additional $180,000 over 30 years, assuming you invest your savings.
Remember, in addition to your monthly payments, you'll be paying for insurance, fuel, maintenance and repairs.
To find out a car's cost of ownership over five years, use
Edmunds.com's True Cost to Own calculator or
Intellichoice's Side-by-side Comparison. 
