WASHINGTON (AP) â¿¿ Americans likely increased their borrowing in March to buy more cars and attend college, while holding off on more credit card debt. Economists forecast that consumer borrowing rose $15 billion in March compared with February, according to a survey by FactSet. The Federal Reserve will release the report at 3 p.m. EDT Tuesday. In February, borrowing rose by $18.1 billion to a seasonally adjusted $2.8 trillion. Nearly all of the February gains were in the category that covers student and auto loans. Consumers have been more cautious about increasing their credit card debt. It remains 17.2 percent below the peak set in June 2008. Economists believe consumers will stay cautious about adding more high-interest debt this year. One reason is higher Social Security taxes have reduced their take-home pay. The credit report doesn't separate auto loans from student loans. But according to quarterly data compiled by the Federal Reserve Bank of New York, student loan debt has been the biggest driver of borrowing since the recession ended in June 2009. Student loans reached $966 billion in last year's fourth quarter, up $10 billion from the third quarter. During the January-March quarter, consumers increased their spending at the fastest pace in more than two years. However, they had to trim the pace of their savings to finance the faster spending. Their after-tax income dropped by the largest amount since the final three months of the recession in 2009. Part of the drop in after-tax income reflected the increase in Social Security taxes that took effect on Jan. 1. The strong consumer spending helped push overall economic growth to an annual rate of 2.5 percent in the January-March quarter. Many economists believe growth is slowing in the April-June quarter, in part because of automatic government spending cuts that began taking effect on March 1.