(MONEY Magazine) – Some financial planners suggest car shoppers borrow by taking out home-equity loans whose interest would be fully tax deductible. Sounds logical, but it's bad advice. Even though the monthly payment will be higher on a car loan, you will pay more, even after taxes, with the longer-term, home-equity loan. Assume you are in the 28% tax bracket and will make a 10% down payment on an $11,000 car in January. A four-year car loan at 10.73% will cost roughly $12,150 after taxes. But a 10-year home-equity loan will cost about $2,400 more after taxes, if the interest rate remains at today's average of 10.98%.

CHART: NOT AVAILABLE CREDIT: NO CREDIT CAPTION: NO CAPTION DESCRIPTION: Information about fixed-rate mortgages, home-equity loans.