No, transportation stocks may not be the sexy stocks people discuss at a dinner party, but that doesn't mean they can't produce sexy results for a portfolio. In fact, many transportation companies are the backbone of our consumer economy. That's (in part) why transportation stocks can be some of the best to own. Here are two to consider that many investors overlook.

One-stop shop

XPO Logistics (NYSE:XPO) may not be a company many investors are familiar with. It's one of the 10 largest global logistics companies, with a massive footprint stretching across 34 countries. The company has two reporting segments: transportation and logistics. Essentially, through multiple services, XPO will help you haul, or explain how you can haul, freight better -- improving productivity and reducing costs.

One thing investors should love about XPO is its ability to cross-sell services. Consider that 87 of XPO's top 100 customers use two or more of its services, and a staggering 38 use five or more. Management, understanding the importance of this, has recently more than tripled its number of strategic account managers and added over 50 local account executives. XPO has also implemented growth-based incentives and training to help sales managers drive more cross-selling services.

Freight being loaded onto trucks while an airplane flies overhead.

Image source: Getty Images.

XPO has grown rapidly over the past half-decade, thanks in large part to its willingness to gobble up companies through acquisitions, including its big-time acquisitions of Con-way and Norbert Dentressangle in 2015. You can see how the moves drove XPO's top line:

XPO Chart

XPO data by YCharts.

Considering that just about every industry requires transportation and/or logistics, management believes it has a $1 trillion addressable market, with XPO currently having a 1.5% market share. Because that's an insanely huge addressable market, XPO could have a lucrative future if it can fold in all of its acquisitions and create cost synergies.

Flying high

If you're looking for a great company trading fairly cheaply, look no further than this airline: Hawaiian Holdings (NASDAQ:HA) is trading at a trailing-12-month price-to-earnings ratio of only 12. That's well below the S&P 500 average of 25, and below the P/E of many of its competitors. Sure, it faces some near-term headwinds, but there aren't many transportation companies not facing a challenge right now (just ask the railroad industry about its coal woes). Hawaiian expects its non-fuel costs per available seat mile (CASM) to jump 4.5% to 7.5% during the second quarter, and its overall CASM to rise 8% to 11%. And with a new pilot contract on the way, Hawaiian Holdings' labor costs are about to rise.

At some point, however, investors have to put their faith in management to offset cyclical costs, and Hawaiian Holdings has done well over the past few years in multiple metrics including revenue per available seat mile (RASM):

Graphic showing HA's RASM leading the industry average

Image source: Hawaiian Holdings' May 2017 investor presentation.

2017 is a bit of a pivotal year for the company, as between 2010 and 2014 it focused almost entirely on investing in its fleet and its business for growth. Since 2015, the company has been making huge strides in paying down its debt. In 2014 its ratio of adjusted debt-to-EBITDAR (earnings before interest, taxes, depreciation, amortization, and restructuring or rent costs) was near the top of the industry at 4.2. That was cut down to 2.4 in 2015, and sits at about 1.9 currently.

Now with a healthier balance sheet, Hawaiian Holdings can continue to invest in its business to fuel further RASM. While year-over-year RASM comparisons will become more difficult, if management can offset rising costs by retiring older and less profitable airplanes, this stock could be a hidden gem in the transportation industry.

Daniel Miller has no position in any stocks mentioned. The Motley Fool recommends XPO Logistics. The Motley Fool has a disclosure policy.