Interested in a Fuel Efficient Car? Estimate how many months it may take to recover the out-of-pocket costs when buying a more efficient vehicle. You are viewing this website at a small screen resolution which doesn't support calculators. Click here to view this calculator. Have A Question About This Topic? Name Email Address Message Thank you! Oops! Related Content What Smart Investors Know Savvy investors take the time to separate emotion from fact. Social Security: The Elephant in the Room Some people wonder if Social Security will remain financially sound enough to pay the benefits they are owed. The Rule of 72 Do you know how long it may take for your investments to double in value? The Rule of 72 is a quick way to figure it out.