The delivery truck sitting idle in the lot loses value by the minute. So does the passenger jet sitting on the tarmac waiting for its next charter.

Carrying either on the books can get expensive fast. That's why many customers are leasing them instead.

The weak economy is both a blessing and a curse for leasing firms.

In tough times, all sorts of businesses think about outsourcing ownership, logistics and maintenance of various equipment, theoretically boosting demand for commercial leasing services that provide such services.

But tough times also dampen overall economic activity, so fewer people travel and fewer goods need shipping. So instead of outsourcing their fleet ownership, many are downsizing. They've been negotiating hard when leases come up -- or not renewing at all.

"Customers just weren't coming to (Ryder Systems (NYSE:R - News)) to rent a truck when a lot of their own fleets were sitting idle," said Kevin Sterling, a transportation analyst at BB&T Capital Markets.

But thanks to long-term contracts, many leasing firms generate high free cash flow in down times. Ryder and others have used that money to buy back shares and make other investments.

Ryder is the largest of the 21 companies in IBD's commercial leasing group. The collection of companies has climbed to No. 51 among IBD's 197 industry groups -- up from No. 82 six months ago -- amid tentative signs that the worst is behind them.

1. Business

Generally, companies in this space own and maintain expensive assets -- trucks, jets or even copy machines -- and lease them to clients in short- and long-term contracts.

In addition to Ryder, the group includes Amerco (NasdaqGS:UHAL - News), parent company of iconic self-moving and storage firm U-Haul.

Another company in the group is McGrath RentCorp (NasdaqGS:MGRC - News), which leases modular buildings for classrooms, offices or storage space.

There's also California First National Bancorp (NasdaqGM:CFNB - News), which provides lease financing, as well as direct leasing of computer systems and other technology assets.

Large commercial trucks can cost $150,000 or more. Jumbo jets cost many millions.

CalFirst says the computer systems it leases out -- central servers, desktop machines and other hardware -- range from $100,000 to $3 million.

Leasing firms typically can buy equipment and systems in volume, for lower costs. That allows them to lease to end-users for less money than customers would spend to own it. Leasing firms generally maintain the goods too.

Outsourcing those messy details helps customers focus on their core business.

Name Of The Game: Provide the latest, most efficient equipment to customers for less than they would pay to own it outright.

2. Market

Though U-Haul caters to the individual consumer, most of the customers in this space are other businesses.

Ryder, for instance, has about 15,000 customers -- everything from small bakeries and flower shops, to global corporations such as Toyota (NYSE:TM - News) and Hewlett-Packard (NYSE:HPQ - News).

That makes the trucking and logistics giant something of a bellwether for the greater economy, says Bob Brunn, Ryder's vice president for investor relations. Unfortunately, those customers are selling fewer flowers, cars and other things that Ryder's trucks help transport.

Still, Ryder sees potential tail winds for the $63 billion U.S. private commercial fleet market.

For one thing, the credit market is tough right now for anyone needing a loan to buy a truck. And those trucks get more expensive all the time.

Federal clean-diesel regulations that went into effect in 2007 sparked a wave of new-truck leasing in advance in 2006. The standards are being ratcheted up again for trucks built next year.

The Environmental Protection Agency estimates that the filters and cleaner-running engines add only $1,200 to $1,900 to the price of a truck. Some in the industry say it costs more, bolstering the case for leasing rather than owning.

3. Climate

The slumping economy has been hard on the transportation logistics sector.

Sales of large trucks that move freight across the country peaked in 2006, according to the Truck Manufacturers Association, before the last cleaner-diesel standard took effect. Sales fell off in 2007 and 2008, as a freight recession took hold.

So even though a new round of higher standards is coming, companies aren't looking to upgrade just yet.

It's tough in the air, too. The International Air Transport Association says air freight tonnage dipped globally in 2008 and will fall harder in 2009. IATA projects a 14.1% decline in tonnage when this year is tallied.

But some air routes are showing signs of an uptick, and the group thinks volumes globally could grow slightly next year.

On land, Ryder has spent the last year getting out of some money-losing supply-chain operations in Brazil, Argentina, Chile and Europe.

The company says this will help it focus on North America, the United Kingdom and Asia.

The firm also has been trying to extend the life of some trucks to get more out those investments.

Still, many parts of the shipping and transportation industry are still struggling with excess capacity, and customers are burdened.

Many of the carriers who lease shipping containers from Tal International (NYSE:TAL - News) are operating at a loss, which makes analysts wonder how long they'll be able to make their lease payments.

Despite rate increases, default risk will remain a primary concern for the container leasing industry, Robert W. Baird analyst Jon Langenfeld said in a research report about Tal.

Leasing companies have responded by shrinking their own fleets. This has helped increase utilization rates and margins. But fewer containers or trucks to rent, even when they're used more often, means lower revenue.

The Irish jet leasing firm Babcock & Brown Air (NYSE:FLY - News) says its seen some late payments. For months, its airline customers have been squeezed by higher fuel prices and lower demand among travelers. Its customers have been cutting fares to keep bodies in seats.

But here again, some see tentative signs that the latest cycle has bottomed.

4. Technology

In some ways, technology is what drives this sector.

Trucks are complex machines. And with every new safety regulation or clean-diesel requirement, they get even more complicated.

They're also stocked with an arsenal of high-tech tools such as onboard tracking systems, collision avoidance sensors and other tools. That makes them expensive to buy and maintain.

The same holds for jets. The latest-generation air freighters move more tons for less fuel than the current-fleet workhorses. That makes them attractive, even when the economy is sour.

5. Outlook

This year, Babcock & Brown Chairman Steven Zissis has sounded bearish on the airline industry he serves. It seemed as though all his customers were asking about was how to get out of leases and downsize their fleets.

But now?

For the first time in several quarters, "our airline clients have started talking to us less about fleet retirements and more about growing their capacity," Zissis said during a conference call with analysts and investors earlier this month.

Airline customers are still strapped, he says, but perhaps not as severely.

Ryder's Brunn says the miles his clients put on their trucks are still down from a year ago. But Ryder is starting to see sequential monthly growth.

That could be a sign of a bottoming out, though the company isn't projecting a rapid rebound in freight demand yet.

Billionaire investor Warren Buffett is making a huge bet on the future of U.S. transportation demand with the purchase of the 131-year-old Burlington Northern Sante Fe (NYSE:BNI - News) railroad.

Railroad companies aren't part of the commercial services leasing group. But if Buffett is right, the demand that spurs railroads should also drive demand for trucks, new warehouses, more roads and other infrastructure.

When the market does turn, Ryder thinks many firms will rethink how they handle vehicle maintenance and logistics.

"I think going forward, companies are going to be very careful in how they use their balance sheets, and that's going to be an argument for outsourcing for us," Brunn said.

Upside: New environmental regulations, as well as tight credit markets, make buying hard -- and leasing more attractive.

Risks: Economic activity must pick up before customers will begin leasing more trucks, planes and computer systems again.

Despite faint whiffs of a rebound, many firms characterize the improvement as things getting less bad, rather than better.