Chrysler, the smallest of the Detroit carmakers, had the best year among U.S. companies. Its sales jumped 21 percent for the year and 10 percent in December. Demand was led by the Jeep Grand Cherokee SUV, Ram pickup and Chrysler 300 luxury car.But full-year sales at Ford and General Motors lagged. GM's rose only 3.7 percent for the year, while Ford edged up 5 percent. For December, GM sales rose 5 percent, while Ford was up 2 percent. GM executives said the company has the oldest model lineup in the industry, yet it still posted a sales increase and commanded high prices for its cars and trucks. The company plans to refurbish 70 percent of its North American models in the next 18 months and expects to boost sales this year. North American President Mark Reuss said the company won't give away cars and trucks with discounts like it has in the past, especially when it's in the midst of its biggest product update ever. "Give us 18 months and you're going to see the whole portfolio turned," said Reuss. Ford said that even though the fiscal cliff deal raised tax rates on individuals making more than $400,000 and couples making more than $450,000 a year, it doesn't see a huge impact on auto sales. Its chief economist, Ellen Hughes-Cromwick, said only 2 percent of new-vehicle buyers have income in that upper tax bracket, and they tend to purchase even if there is a change in their after-tax income. She said Ford is more concerned about an increase in the payroll tax, which is scheduled to bounce up to 6.2 percent this year from 4.2 percent in 2011 and 2012. That amounts to a $1,000 to $1,500 tax increase per household, she said. "We will look at that closely because it will crimp spending in the months ahead," she said.