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 How Will Working Affect Social Security Benefits? Knowing the rules may help you decide when to start benefits. 18 Years’ Worth of Days The average retirement lasts for 18 years, with many lasting even longer. Will you fill your post-retirement days with purpose? The Cycle of Investing Understanding the cycle of investing may help you avoid easy pitfalls.