The average car-driving family is expected to save about $550 this year on gas, thanks to rapidly plunging oil prices. Unfortunately, that's not the case for the typical small business.

While businesses that operate fleets of automobiles are certainly slated to save some money, businesses that depend on airlines or trucks to ship packages won't see much by way of cost reductions. Nor will people who travel a lot for business on airlines.

The two major U.S. shippers, FedEx and UPS, are actually raising prices despite significant savings to their bottom line from cheap oil. Similarly, major airlines haven't decreased ticket prices, despite savings on airplane fuel. And some business owners who use petroleum in their products aren't saving any money.

"Even with the cost of oil going down, my manufacturers won't lower prices," says Julie Austin, founder and chief executive of HydroSport, a Los Angeles-based maker of wearable water bottles called Swiggies.

Austin manufactures her product, which is petroleum-based, in Malaysia and China. She says that when oil prices spiked four years ago, to about $110 a barrel from around $70, her manufacturers raised prices, citing the rising cost of oil. Given how far prices have fallen in this go-around, she expected to save as much as 20 percent on her production costs.

Prices for oil, currently around $50 a barrel, have fallen by half since July 2014, when the price per barrel was about $100.

Meanwhile, FedEx and UPS--the largest package shippers in the U.S.--are both raising prices. The companies have raised ground, air, and international rates 5 percent for 2015. They have also increased surcharges across the board for things like additional handling, delivering to more remote areas, and delivery confirmations.

For its part, UPS has actually increased its fuel surcharges. In the third quarter of 2014--when the price per barrel dropped to $90 a barrel from $100--UPS increased fuel surcharges to 10.3 percent for next-day air delivery, and to 7.2 percent for ground delivery, which represent an increase of 0.3 percent and 0.2 percent respectively for the three months ended September 30. For the same three months, UPS reports domestic fuel-surcharge revenue increased by $28 million.

In response to questions about the rate increases, a UPS spokesman referred Inc. to comments made by the company's chief financial officer, Kurt Kuehn, during an analyst earnings call on February 3. Kuehn said that the decreasing cost of oil would have a neutral impact on UPS's bottom line. 

"It's not a huge issue for us over the long term directly, but indirectly certainly, low fuel is a great spark for both consumers and businesses," Kuehn said. 

Similarly, FedEx reported in its November earnings filing with the Securities and Exchange Commission that it paid $54 million less in fuel charges for the three months ended November 30, 2014, and $70 million less for the six months ended November 30. It also reported that fuel costs decreased 8 percent for the same three months, and 3 percent for the six months ended November 30. It decreased its average fuel surcharges in the quarter by 1.33 percentage points for domestic deliveries and by 1.2 percentage points for international deliveries. FedEx, however, suggested such charges were always subject to change depending on market conditions. 

A company representative referred Inc. to the FedEx website, where a section on fuel surcharges says there is a two-month lag between FedEx's fuel surcharges and fuel prices. That could indicate surcharges might go down further in the future.

Meanwhile, the average cost of a domestic airline ticket, an important metric for business travelers, was $396 for the third quarter 2014, up about 30 percent compared with the same period in 2009, when the U.S. was still mired in recession. It's also up 8 percent compared with the third quarter of 2012.

"Usually prices don't go down as fast as they go up," says Kathryn Kobe, director of price, wage, and productivity analysis for business advisory Economic Consulting Services in Washington, D.C. She adds that FedEx and UPS typically increase fuel surcharges when oil prices rise, and they may be reluctant to return profits to anyone but shareholders in the short run.

Ultimately, however, if the price of oils stays down long enough, shippers and airlines could break away from the pack.

"Eventually you may see an airline decide they would rather have market share, and you could see a break in prices based on the fact that their operating costs are down," Kobe says.