Fewer than one in three American consumers – 30% – said in a survey sponsored by Lending Tree they comparison-shopped for major loans such as auto or mortgage loans.

On the other hand, 92% told the firm's poll takers they have comparison-shopped for other items online before purchasing them offline.

“It's an interesting phenomenon,” Lending Tree's consumer savings expert, Andrea Woroch, said. “Consumers are generally very savvy with their shopping behavior when it comes to day-to-day purchases and material goods. But, once it comes to a major financial investment, we see a collapse of the normally rational pattern of behavior and mentality for saving.”

She continued, “Consumers sometimes may be too focused on price and fail to consider the lifetime cost of interest which is really where banks and lenders make their money. Over a five-year auto loan, or 30-year mortgage, a 1% difference between interest rates can easily translate to thousands of dollars.”

The Charlotte, N.C.-based online lending firm, which has partnered with credit unions in the past, estimated the average consumer who buys a home could save roughly $17,000 over the life of a loan if he or she compared mortgage rates and terms before agreeing to sign.