Chipotle Mexican Grill (NYSE:CMG) made huge gains in the most recent quarter, with earnings up an exceptional 49% year over year. This amazing growth in earnings comes on top of over 30% growth in year-over-year revenues, a level of fresh growth that a more aged competitor like McDonald's (NYSE:MCD) has very little chance of ever seeing again. This exceptional growth in Q3 and the rest of 2014 has helped to push Chipotle's stock price to a premium of over 50 times earnings. But is it possible for Chipotle to repeat these feats of growth in 2015? Probably not. Yet here is why the stock still looks worth its price.

Lowered 2013 earnings are making 2014 results look really good
Chipotle's third-quarter results were very impressive, with massive gains in total year-over-year revenue and income. These increases in revenue and income came mainly from growth in same-store sales, which rose nearly 20% YOY, ahead of the expected 17.3%.

Coming up to Q4, is it possible that Chipotle will be able to repeat these results? For the next quarter, maybe, but for the next year, most likely not. The main reason these results look so amazing is that earnings and revenue took a small dip in 2013, making this year's results look extra good in comparison. During Q3 and Q4 of last year, total income for the company actually fell from the at-the-time high of nearly $90 million, and didn't start rising again until Q1 of this year. 

CMG Net Income (Quarterly) Chart

CMG Net Income (Quarterly) data by YCharts

Because Q4 2013 results were still on the decline, Q4 this year might actually be just as impressive, or even more so than this recent Q3, at least in terms of year-over-year growth. But in 2015, while the company is likely to continue growing rapidly, don't expect that the company can continue to notch these same amazing-looking year-over-year results again.

But the stock still looks like a long-term buy
Even though the amazing year-over-year results Chipotle reported in Q3 this year, and might report again next quarter, are probably not repeatable in 2015, the stock still looks to be a long-term buy on what should be massive growth over the next few years.

While the Q3 results of massive growth might seem like a fluke, the five-year growth looks very strong. For one thing, the company has continued to grow earnings nearly constantly, other than the last two quarters of 2013. Over the last five years, the company has grown earnings substantially.

CMG EBITDA (Annual) Chart

CMG EBITDA (Annual) data by YCharts

So, what could the stock be worth in the next few years? From these impressive gains in revenue and earnings, Chipotle has consistently grown its free cash flow (FCF). With FCF growth of around 23% in the last three years, with little worry of lowered EBITDA or rising debt, the company can likely continue growing FCF by at least 15%-20% in the next few years. It's impossible to know what the market will do, but if that is the case, this supports a valuation of over $1,000 in five years, assuming the current price to free cash flow rate of about 40 times is held constant. Chipotle shares closed Dec. 2 at $660.

Worth the premium compared to a cheaper competitor like McDonald's?
Chipotle's stock's run in the last five years has priced the stock at a premium of over 50 times earnings. Compare this to McDonald's P/E of just 18 times, and you might wonder if Chipotle's stock is still worth its premium price.

CMG Chart

CMG data by YCharts

From the analysis above, Chipotle stock still looks to have a potential 50% upside by 2019. And where will all of this growth come from? With a growing number of U.S. locations, expected to be more than 200 in 2015, continually rising same-store sales, growing opportunity in small chains like Pizza Locale and Chophouse, as well as plenty of opportunity for international expansion, Chipotle still seems to have plenty of growth left.

Compare this likely growth in Chipotle's revenues and earnings to the potential growth of McDonald's. While McDonald's does continue to grow internationally, the most exciting news for McDonald's in its recent history is when it reintroduces the oh-so-savory McRib sandwich. With expected earnings growth of about 6.8% in 2015 over 2014, there looks to be a reason that McDonald's is selling so cheap compared to Chipotle, which maintains an expected 2015 earnings growth rate of 24%. 

Following a great 2014, Chipotle probably won't be able to show more quarters of nearly 50% income growth during 2015. Yet for those investors looking to get in on a stock that still has vast growth potential, Chipotle is a great pick even at a premium price compared to McDonald's.

Bradley Seth McNew has no position in any stocks mentioned. The Motley Fool recommends Chipotle Mexican Grill and McDonald's. The Motley Fool owns shares of Chipotle Mexican Grill. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.