Stock index futures were flat on Tuesday as investors awaited key economic data for fresh signs of an economic recovery a day after the Dow and the S&P rallied to their highest closes in more than 15 months.

Investors will get a better picture of the state of consumer spending as automakers report U.S. vehicle sales for December. Economists surveyed by Reuters expect median annualized domestic sales of 3.90 million cars and 4.45 million trucks, slightly higher than 3.87 million cars and 4.44 million trucks sold in November.

The Commerce Department is to report November factory orders at 10 a.m. EST. Economists see a rise of 0.5 percent, compared with a 0.6 percent gain in the prior month.

Kraft Foods Inc sold its North American frozen pizza business for $3.7 billion to Swiss food giant Nestle AG and sweetened its offer for Britain's Cadbury Plc . Nestle said it does not intend to bid for the British confectioner, ending speculation of a potential rival offer.

January is an important month in terms of being an indicator on how the rest of the year would trade, and we started off well ... The market is going to focus on improving economic data, and less on the threats of higher interest rates or reduction in global monetary stimulus, said Peter Boockvar, Equity Strategist at Miller Tabak + Co in New York.

S&P 500 futures rose 1.5 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures rose 1 point, and Nasdaq 100 futures gained 2 points.

The National Association of Realtors will release pending home sales for November at 10 a.m. EST. Economists look for a 2.0 percent decline, compared with a 3.7 percent rise in the previous month.

RadioShack Corp shares gained 6.5 percent to $21.05 in premarket trading after Goldman Sachs upgraded the stock. Tenet Healthcare Corp rose 10.1 percent to $6 after Goldman added the stock to its conviction buy list.

Google Inc is expected to unveil its highly anticipated smartphone in its first foray into an increasingly crowded market that could shape the future of the company's advertising business.

Apple Inc is set to release a new tablet device later this month, the Wall Street Journal reported Monday, as anticipation builds about its next big product launch since the iPhone.

(Reporting by Angela Moon; editing by Jeffrey Benkoe)