Chipotle Mexican Grill (CMG -1.34%) has once again pleased investors with its impressive fourth quarter earnings results. Right after the earnings announcement, Chipotle's share price was up by nearly 13.30% in after-hours trading, to $559.50 per share. Its earnings results were indeed much better than those of its quick service restaurant peers McDonald's (MCD 0.37%) and Yum! Brands (YUM 0.46%)

Chipotle's operating performance is much better than those of McDonald's and Yum! Brands
Chipotle reported that it delivered total fourth quarter revenue of $844.1 million, beating analysts expectation of $826.3 million, while it earned around $2.53 per share in the fourth quarter, one cent higher than analysts' estimates of $2.52 per share. Its comparable store sales saw high single digit growth, at 9.3%, much higher than the comp store sales growth expectation of only 6.7%. 

On the other hand, McDonald's announced that it had a fourth quarter profit of $1.4 billion, nearly flat compared to the same period last year. Its EPS experienced higher growth, from $1.38 last year to $1.40 this year, but that was driven by share buyback activity. McDonald's sluggish fourth quarter earnings were mainly due to a 0.1% decline in global same restaurant sales and rising expenses.  Yum! Brands reported that its third quarter EPS declined by 15%, and the company also reduced full year EPS expectations due to a slowdown in KFC China sales and a higher tax rate. Yum! Brands has huge exposure to China, which contributed more than half of the company's overall profit. Thus, any volatility in the Chinese business environment could significantly dampen the company's overall profitability. 

Key growth drivers for this quick service restaurant chain
Looking forward, Chipotle will continue to focus on introducing healthier foods and healthier eating habits to consumers. First, Chipotle has consistently tried to remove all GMO (genetically modified foods) ingredients from its food. It is also shifting its ingredient sourcing to non-GMO items in the future. The company proudly reported that all of its cooking oils in North America were made from non-GMO ingredients. Second, it introduced Sofritas, the organic artisan tofu, in the San Francisco Bay Area last year. Within less than a year, Sofritas has become available in more than 40% of Chipotle's restaurants and accounted for 3% of total sales. The company has also succeeded in converting customers who normally eat meat to trying the healthier Sofritas. Those customers represented as much as 40% of total Sofritas sold.

Moreover, Chipotle also introduced the new concept, ShopHouse Southeast Asian Kitchen, to serve customers with different food specialties from Thailand, Malaysia and Vietnam. It also invested into Pizzeria Locale to expand its food offerings to pizza with the same type of customized and fast Chipotle-style service. In 2014, the company intends to open more ShopHouse restaurants in Los Angeles and Washington D.C, and a couple of more Pizzeria Locale restaurants later this year as well. 

Valuation-wise, Chipotle seems to be quite expensively valued, at nearly 35 times its forward earnings. McDonald's and Yum! Brands has much more reasonable forward earnings valuation, at 14.8 and 18.5, respectively. While Chipotle does not offer investors any dividend, McDonald's and Yum! Brands could fit well in income investors' portfolio with decent dividend yield, at 3.40% and 2.20%, respectively.

My Foolish take
Chipotle Mexican Grill could be suitable only for growth investors, as it provides no dividends and fetches quite a high forward earnings multiple. In the long run, healthier eating options and new exciting restaurant concepts such as ShopHouse and Pizzeria Locale are important growth drivers for Chipotle's future.