What: Shares of Swift Transportation (NYSE:SWFT) have climbed 16.5% as of 11:15 a.m. ET today after posting healthy earnings results that surprised Wall Street.

So what: Before the market opened today, Swift announced it had generated earnings per share of $0.51 per share for the fourth quarter, beating analysts expectations of $0.47 per share. While the company did see operating revenue decline slightly compared to the same quarter last year, fuel cost savings and other cost-cutting helped in improving margins and year-over-year profits.

What is likely going overlooked, though, is that some of its non-fuel related costs have increased as of late. Wages & salaries increased 10% compared to this time last year, to $290 million, and operating supplies & expenses are now above 10% of revenue.

Now what: Let's keep today's share price spike in perspective. The company's shares are still down 45% compared to this time last year. So, it will take a lot more than today's spike to recapture the company's losses in 2015.

SWFT Chart

SWFT data by YCharts.

As good as these numbers look, though, one thing to keep in mind is that savings from fuel costs are a cyclical thing, and not sustainable over the long term. So, investors who are impressed with these recent results should enjoy the spoils of cheap fuel now, but don't let it change anything about the overall thesis for the company.