NEW YORK (TheStreet) – With cheap gas fueling better-than-expected results from Delta Air Lines (DAL) , expectations are soaring for Spirit Airlines (SAVE - Get Report) , which reports fourth-quarter and full-year results Tuesday.

Spirit shares, closing Friday at $77.44, are up 2.46% year to date, besting both the Dow Jones Industrial Average (DJI) and the S&P 500 (SPX) , which have traded flat.

Nonetheless, Spirit shares have traded flat over the past three months, giving investors a rare buying opportunity. These shares, which are up 68% in 12 months, never get cheap. And with Delta benefiting from cheap gas, which lowered its fuel costs, Spirit stock is likely to take off Tuesday from this same effect. And investors on the sidelines don't want to get left behind.

Part of the reason, Spirit, headquartered in Miramar, Fla., is not your typical airline stock.

The company grew earnings at over a 60% rate last year. And not only is it projected to grow earnings this year at more than 32% year over year, analysts project Spirit to grow earnings at an annual rate of 36% in the next five years. That's more than twice the 16% projected annual growth rate of United Continental (UAL) and 15 percentage points higher than Southwest Airlines (LUV) .

By that standard, Spirit shares, which have a consensus buy rating, are still undervalued, even after posting almost 300% gains in the past three years.

The company has developed a unique and disruptive low-cost business structure that has paid off handsomely for shareholders because Spirit is able to maintain high profit margins. The company calls it a “Frill Control” model, which benefits customers because they are “never stuck paying for extras they didn’t ask for.” Wifi connectivity is one example.

Because of this, not only is Spirit able to offer dirt-cheap air fare, the company is then able to generate 40% of its revenue from add-ons, like carry-on luggage and checked bags.

In other words, unlike other airlines that want to model themselves as a five-star hotel, Spirit celebrates that it is a small motel for customers who couldn't care less about marble ceilings. And with fuel costs being roughly two-thirds of its expenses, to the extent Spirit was able to lower its biggest overhead, the company is certain to beat estimates Tuesday.

For the quarter ending in December, analysts will be looking for 78 cents per share in earnings on revenue of $477 million, representing year-over-year growth of 39% and 13.7%, respectively. For the full year, earnings are expected to surge 32% year over year, while revenue is seen climbing roughly 17% year over year to $1.9 billion.

What stands out here is that, earnings are projected to grow at roughly twice the rate of revenue for both the quarterly and full-year result. This is an example of a well-managed company -- one that knows how to return value to shareholders by eliminating waste and operating efficiently, making it one of the best stocks to own on the market.

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This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.