That's when he pulls up, only to find the passenger isn't at the appointed place. What's particularly galling is people calling Salt Lake City's three taxi companies - then getting into the cab of the driver who shows up first.

"People may not understand that we have to buy our own gas," said Mohammed. "And the gas prices are killing us."

Squeezed by skyrocketing gasoline and maintenance costs, passengers can do their part in helping cab drivers make a living by using a little common sense, cabbies say. In short, if you've called a cab, show up. And if possible, don't forget to tip: 15 percent to 20 percent is recommended.

Mohamed, an eight-year veteran, said he knows about the economy slowdown from the amount of tips he collects. He gets about half the amount from what he received two years ago.

To make up for the fewer tips and higher gasoline costs, he works an extra two or three hours each day.

Mohamed appreciates passengers who show courtesy. If, for instance, someone doesn't need a cab that's already been summoned, a generous tip would help defray gasoline costs the cabbie needlessly burned up for the No Go trip.

Hal Morgan, vice president of the Washington-based Taxicab, Limousine & Paratransit Association, said cab drivers throughout the nation get similarly stiffed, making the No Goes cabbies' biggest complaint.

Cabbie Felicia Niculescu recently drove to LDS Hospital to pick up a passenger. But when she got there, the woman told Niculescu that someone else had offered to take her home. Niculescu drove away, empty handed.

She had to pick up the costs for deadheading - driving without a passenger - to get to the hospital and then to pick up her next fare.

Deadheading adds up quickly, particularly outside of the city limits. It's a longer trip to pick up someone hailing a cab, say at a grocery store around 2700 South. The fare barely covers the cost when the passenger's home is a mile or so away from the supermarket.

"Driving is like gambling," said Niculescu, who has driven for 12 years. "What you make depends on how lucky you are."

Tips are always appreciated, particularly during the summer when many residents and tourists opt to walk. As the weather warms, the taxi business can go down by as much as 40 percent.

Niculescu recently was rewarded by the gesture of an elderly passenger who had caught a ride to the grocery store. The woman told Niculescu that she wished she were rich so she could tip more - as she handed her cabbie a single quarter.

Back-seat etiquette

* Do ask for an estimated cost of your ride.

* Don't be impatient, a traffic jam isn't the driver's fault.

* Do pay for the gasoline if you decide not to take the cab you called for.

* Do keep your cell phone on if the driver needs to find you.

* Do record the taxi number in case you have left something behind.

* Don't forget the most common item left in cabs, cell phones.

* Do tip, 15 percent to 20 percent is recommended.

Source: Yellow Cab

Fast facts - nationally

* About 6,300 companies operate 171,000 taxicabs.

* 80 percent of the companies operate less than 50 vehicles.

* 6 percent are large operations with more than 100 vehicles.

* Taxicab companies provide work for 350,000 people.

* Cab drivers transport 1.4 billion passengers annually.

Source: Taxicab, Limousine & Paratransit Association