Shares of General Motors rose more than 2 percent Tuesday after a slew of analysts advised buying shares of the automaker, which has raised $23 billion recently in the world's largest IPO.

Banks that underwrote GM's initial public offering in November were restricted from initiating coverage on the company for 40 days after the stock started trading. With the coverage ban being lifted, analysts have expressed their thoughts on the new GM.

Credit Suisse initiated coverage of automaker General Motors (GM) with an 'outperform' rating and price target of $43, saying the stock offers an attractive investment opportunity.

After a quick stint in bankruptcy, the primary outcome of which was a balance-sheet cleansing and the installation of new management and Board, we think GM offers an attractive 12-18 month investment opportunity, analyst Christopher Ceraso wrote in a note to clients.

On the valuation front, the analyst said GM still came to market at a deep discount to rival Ford (F). GM stock is currently trading at 3.9 times to 2011 earnings before interest, taxes, depreciation and amortization (EBITDA) , whereas Ford is trading at 5.5 times to EBITDA.

However, the analyst said the valuation gap between GM and Ford will close in 2012.

.. we think GM's current discount to Ford is justified, but that the gap will close materially in 2012 as GM's product cycle hits its stride and Ford's shifts to a lower gear.

Also, Barclays Capital started GM with an overweight and set a price target of $42 per share, citing the company's strong positions in emerging markets such as China and Brazil.

JPMorgan, like Barclay's, initiated GM's coverage with overweight rating and set a target price of $44 per share, citing GM's strong position in emerging markets and sees the potential for significant additional appreciations beyond year-end 2011.

In November, GM priced its IPO at $33 per share.

2011 Won't Be Easy For GM

Credit Suisse analyst Ceraso said though he recommends investors build positions ahead of the expected 2012 re-rating. Ceraso expects that 2011 will be a difficult year for GM as the company has limited new product coming to market this year and faces difficult production comparisons versus 2010, when the company was re-stocking depleted truck inventories.

Also, Ceraso noted that GM's pension plans remain under-funded by more than $20 billion globally, and thus will consume significant cash contributions over the next two years.

On the opportunity side, we note that normalization of record-low interest rates could shrink GM's liability, potentially freeing up significant value for equity holders, the analyst said.

GM, once a blue chip stock, lost its number one automaker by sales status to Japan's Toyota. Adding to the woes, the 102-year old company was hurt by falling sales amid a sharp US recession, resulting in a government-backed bailout.

However, the GM's return to the market comes at a time when auto sector is rebounding amid improving car sales.

But GM is improving. It was losing over $3,500 a car before bankruptcy, but it is now earning over $1,700 each car and the automaker is set to earn about $19 billion a year when the car market rebounds.

With a new business model, centered around designing, building and selling the world's best vehicles, we're ready to compete and are confident about the company's future, said CFO Liddell.

GM, which is still one of the world's largest automakers, traces its roots back to 1908.  With its global headquarters in Detroit, GM employs 209,000 people and does business in more than 120 countries.

The company's shares resumed trading on the New York Stock Exchange on Nov.19. Dan Akerson is leading GM's new management team and also the company's fourth CEO in two years.

Shares of GM closed Tuesday's regular trading session at $35.32 on the NYSE. Since going public last month, GM shares have traded between $33.07 and $35.99.