Retirement savers are often warned about the impact of health-care and housing costs, but there’s another major expense Americans need to plan for as they age—transportation.

Transportation costs, regardless of income, account for 14% of expenses for retirees, on average, according to the Social Security Administration’s “Expenditures of the Aged Chartbook,” which is based on data from the 2010 Consumer Expenditure Survey Public-Use File.

Now at first glance, that might not seem to be a large expense. After all, housing is at 35%. But after housing, transportation is the average retiree’s second-largest expense in retirement. And it’s an especially big expense and issue for older Americans who live in rural areas and don’t have access to public transportation, according to Joe Coughlin, director of the MIT AgeLab. He spoke recently (as did I) at the Financial Communication Society’s 5th Annual Education Summit.

So what can you do to tame transportation costs in retirement? Here’s what experts had to say.

How much do you spend on transportation?

The average retiree household spends 14% on transportation, but you might spend more or you might spend less. But you won’t really know until you crunch the numbers. “We always encourage that pre-retirees complete a very comprehensive budget which includes transportation costs so that they are fully prepared when faced with the cost,” said Gavin Morrissey, a senior vice president of wealth management at Commonwealth Financial Network.

Others note how such costs can be budget busters. “Transportation costs can add up for retirees,” said Suzanna de Baca, vice president of wealth strategies and marketing for Ameriprise Financial. “Those expenses can range from simply getting around town for day-to-day errands to the cost of travel to see family, friends or sites.”

Time to get creative

No matter what you spend on transportation, it’s likely that you take it all for granted. You likely drive to work, to malls and to the movies without thinking twice about it. But that may have to change in the future, or at least it might have to change for those who want to keep their transportation costs in retirement in check.

“It’s time for all of us to be creative about where we drive and how frequently,” said Sandra Timmermann, vice president and director of the MetLife Mature Market Institute.

In the future, Timmermann and others say, retirees and pre-retirees will need to consider planning their trips more carefully, and grouping errands together. They might, for instance, check with neighbors if they just need a few groceries, or take turns with friends driving to the store, going to social events, and the like, Timmermann said.

Like Timmermann, Karen Wimbish, director of retail retirement for Wells Fargo, recommends that retirees and pre-retirees consider carpooling and ride sharing. “Go grocery shopping with friends and share the cost of gas or alternate the use of cars,” Wimbish suggested.

“In the same way that people are sharing housing costs, they may also be able to share transportation expenses,” said Shannon Reid, director of retirement solutions at Raymond James Financial.

So, for example, if you no longer need to have a car to commute to work every day, car sharing or carpooling can become easier options with the more flexible schedule of some retirees, Reid said.

And don’t be shy about looking for carpooling buddies. “If you are commuting to daily or weekly activities like exercise classes or volunteer opportunities, near where you live consider sharing a ride with a friend who is doing the same activities,” said de Baca. “Ask around and you may find that others are also looking for a driving companion.”

And, if you live in the city, consider sharing cab rides.

Who needs two cars anyway?

Retirees should also evaluate whether they need two cars for one household. “With both spouses no longer working there may be more schedule flexibility which may allow for their transportation needs to be met with one vehicle,” said Morrissey.

Wimbish said another way to trim transportation costs—at least for those who are able—is to walk more.

Consider public transportation

If you are planning to retire to another location, consider not only tax rates and climate but also whether there’s public transportation. “Will there be shuttles to places such as grocery stores, church, and shopping centers?” asked Wimbish.

Others share that point of view. “While moving isn’t an option for many people, relocating to an active adult community near amenities or with its own transportation services or to a downtown area where stores and restaurants are within walking distance could be a good choice for a number of reasons,” Timmermann said. “In addition to the benefits of saving money on transportation, being closer to services and near other people is an antidote to social isolation.

De Baca also thinks public transportation is a viable way to cut costs. “Depending on where you live, public transportation can be a convenient and inexpensive way to get around,” she said. “Bus, train, or trolley systems can be safe and offer reasonable fares.”

In addition, de Baca recommends exploring community-sponsored senior transportation. “Some communities offer transportation options to seniors, such as van services or even vouchers or sliding scale fees for public transportation,” she noted.

Plan ahead/shop around

It might seem a bit obvious, but if you’re retired don’t forget to plan ahead for air travel. “Discount airfares are available for those who plan ahead or shop around,” said de Baca. “If you know your travel plans in advance, lock in attractive rates by exploring fare deals or looking for travel packages.”

Also, shop around for car insurance. “If you are still driving a car, consider shopping around for auto insurance,” said de Baca. “You may be surprised at how competitive the marketplace is and be able to shave some cash off your fixed expenses.”

Transportation costs fall over time

There is one other item to consider about transportation costs in retirement. Those costs are likely to fall from 14% of expenses to less than 10% over the course of retirement, as people age and become less mobile. “With retirement, daily transportation needs (such as commuting to work) fall to a great extent, and with increasing age and declining health people become more restricted to the indoors, which cuts entertainment expenses,” wrote Sudipto Banerjee of the Employee Benefit Research Institute in 2012. Read Banerjee’s report, Expenditure Patterns of Older Americans, 2001‒2009.

Median transportation spending in 2010 dollars, and mean percentage:

Source: Employee Benefit Research Institute estimates from the Consumption and Activities Mail Survey, 2001-2009.

Robert Powell is editor of Retirement Weekly, published by MarketWatch. Learn more about Retirement Weekly here. Follow his tweets at RJPIII. Got questions about retirement? Get answers. Email rpowell@marketwatch.com.