Source: Chipotle Mexican Grill.

Through good times and bad, Chipotle Mexican Grill (NYSE:CMG) has been the darling of the restaurant industry, with its fast-casual approach to the business resonating strongly with customers seeking high food quality and great taste. With the chain getting top ratings from key demographic groups including millennials and other younger-generation patrons, Chipotle has set itself up with a loyal customer base for decades to come. Yet even as Chipotle expands, the question remains whether the company can sustain its current pace of growth, or whether an inevitable slowdown will finally cause Chipotle's stock to fall. Let's examine how 2014 went for Chipotle Mexican Grill and whether 2015 can give investors more of the same in terms of solid returns.

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Chipotle keeps spicing up its stock

Chipotle Mexican Grill has defied expectations from skeptical analysts for quite a while, managing to produce impressive gains in revenue and profits even as the chain continues to grow. In its most recent quarter, Chipotle saw sales climb more than 31%, with comparable-restaurant sales coming in just below 20%. That by itself crushed most of Chipotle's competitors, but in addition, Chipotle has done an even better job of ensuring that as much of its revenue as possible falls through to the bottom line. Net income soared almost 57% for the quarter.

One key to Chipotle's success has been that the company learned early on that company-owned stores would allow it to maximize its profit potential from the success of its restaurant concept. In stark contrast to many franchised fast-food chains, which have to share total profits with franchisees, Chipotle is able to benefit directly from its company-owned locations and can also ensure that key measures like quality control and personnel management don't vary from location to location in a way that will hurt the overall brand.

Moreover, by keeping things simple, Chipotle avoids some of the competitive tricks that trap its rival restaurant chains. Chipotle's menus are limited, and its restaurants aren't all that large. But with an employee culture that offers good pay and substantial benefits compared to its peers, Chipotle emphasizes speedy customer service and consistent preparation techniques that maximize profit margins.

Source: Chipotle Mexican Grill.

Can Chipotle keep growing this fast?

One concern that many investors continue to have is whether Chipotle's growth will slow down in the near future. In the aftermath of Chipotle's most recent earnings report, shares fell sharply because of somewhat gloomy guidance that the company gave for the current quarter. Yet rather than spending time obsessing over business metrics, Chipotle's management remains laser-focused on improving the customer experience and making sure that it keeps its quality as high as possible. In addition, by treating its employees well, Chipotle has built up a culture that its customers respect and are willing to pay premium prices to support.

Moreover, Chipotle is working to give diners different eating experiences. With new chains that include its ShopHouse Southeast Asian Kitchen concept and its recent collaboration with craft-pizza maker Pizzeria Locale, Chipotle hopes to give its customer base more choices while still promising the same attention to quality that its loyal customers have come to expect from the chain.

Source: Pizzeria Locale; ShopHouse Southeast Asian Kitchen.

Perhaps most importantly, Chipotle has a track record of defying those who didn't believe in the chain's growth potential. Two years ago, hedge-fund manager David Einhorn infamously predicted that fast-food Mexican specialist Taco Bell would prove to be the straw that broke Chipotle's back by moving toward higher-priced menu items. Yet time after time, Chipotle has simply moved forward with its basic strategy, and that's been enough to sustain growth at current levels. With initiatives like using smaller restaurant footprints to maximize efficiency, Chipotle continues to find new ways to grow and reach increasingly aggressive goals for the future.

Chipotle Mexican Grill has inspired high expectations among its shareholders, and it's almost inevitable that the company will disappoint its investors at some point in the future. Over the long run, though, Chipotle has the ingredients it needs to keep extending its reach and delivering a high-quality dining experience to greater numbers of people across the nation and around the world. That bodes well for Chipotle's long-term prospects going forward into 2015 and beyond.