(FORTUNE Magazine) – I'm bouncing along in a rattly van, heading east from the Los Angeles airport to a rental-car lot on Century Boulevard. I've traveled this route many times before on my way to pick up some soulless compact from Avis or Hertz. But this time's different: I'm straying into the expanding world of luxury car rentals--a place where Ferraris stand in for Fords, and BMWs for Buicks. For business travelers, luxury class is no longer limited to Lincoln Town Cars and Chrysler LeBarons. Who besides me takes advantage of this service? "National and international moguls/magnates," as one company puts it, "with discriminating tastes, generous expense budgets, and very high levels of discretionary income."

Okay--given that I'm a writer, one out of three isn't terrible. So for the sake of journalism, I set off in search of the best deals. Going through "exotic" dealers, and in some areas Budget and Enterprise, discerning drivers can charter a Volvo 850 for $99 a day or, for a real out-of-body (and -pocket) experience, a Bentley Turbo R for $1,700. Hence my trip to L.A.: While it's true that I might have scoped the high-end auto scene from any number of business hubs (see table), why mess around with Vegas when you've got a straight shot to the world's macho mobile mecca?

I have three tough days ahead, so thankfully, much of my research is complete. Back in New York City, phone calls to top hotel concierges and travel agents had yielded the names of several high-end rental places in town, as well as in Miami, San Francisco, New York, and Las Vegas. I learned I could rent a current-model steed by the day or by the week. Automatic or stick. With or without a driver. I could pick up my convertible Hummer myself or arrange to have it delivered to my hotel, gratis. I even found one place in Miami, Excellence Luxury Car Rental, that sends slinkily clad women to greet customers at the airport gate.

My first stop is Midway Car Rental, where I'm booked for a Benz. When the van drops me, the seedy airport outpost hardly seems like a mogul magnet. I forgive the humble surroundings, though, when I see my coach: a soft-gold 1997 Mercedes E320; its wide-eyed headlights beckon me.

Details first. As I sign the contract for $225 a day, I'm thinking how my boss will appreciate the bargain I've snared. Midway's rate for the E320, including insurance (more on that later) but not taxes, is about $40 cheaper than at Budget. Since depreciation is death in the luxury-car business, I'm allowed just 50 free miles a day, after which I'll get nicked 50 cents per mile. But I'm getting what I paid for: The amenities are so-so. There's a moon roof but no CD player or car phone. Some outfits, I know from my research, load their cars with everything from phones to navigational systems.

My hotel's concierge tells me that another place on my list, Luxuryline, is just down the street. I arrive on foot, unannounced. It takes me a minute to achieve eye contact with Derek, who is shouting over a bunch of silly-ringing phones. He answers my questions about models and rates--Luxuryline has topnotch four-doors, convertibles, and 4x4s at $70 to $600 per day--but Derek isn't wasting too much energy on a walk-in. He perks up when a Jeep Wrangler rolls onto the lot. "Hey! You're in disguise today!" he chimes to the headrag-sporting regular. The walk-in routine apparently gets you nowhere in this town. Unless you pull your Benz right up to the door.

I try this tactic at Budget of Beverly Hills, a place that's hard to miss, thanks to the RENT ME signs propped in the windshields of the Dodge Vipers and Lexuses out front. Clearly this is no ordinary corporate-run Budget. The franchised location has a fleet of more than 400 luxury cars, by far the city's largest. As I take a seat inside, I'm quick to tell Juan that my Benz is from a competitor. But my--ahem--business will keep me here another week. What can he offer? Maybe, he suggests, BMW's hot little Z3? When I tell him I've seen it for less than Budget's $163 rate, he says he can haggle a bit, possibly down to $150. Then Juan lets me squeeze into the cockpit of a Viper roadster, which goes for $432.50 a day. "It's an awesome car," purrs Juan. "But not everybody can qualify."

Welcome to the car caste system. Plebes need not apply for patrician wheels. Nor should anyone under the age of 25. Most outfits are picky, picky, picky about customers, demanding credit lines of up to $25,000 on a major card and airtight references. Vogel's Eurocars, based in Yonkers, New York, even posts a $2,000 "radio deposit" on renters' cards, on top of its $225-and-up daily rates. "These requirements help run away the bad people," explains Raymond Mitri of Excellence. Most places expect drivers to provide their own auto insurance. For non-owners like myself, insurance is sometimes available but at near-prohibitive cost: typically $50 to $150 per day, with deductibles as high as $15,000.

On Saturday morning, Midway comes to retrieve my Benz. I'll miss it but won't shed tears. After all, I'm primed to plunk down $425 to trade up to a day in the envy-inspiring Jaguar XK8 convertible. Alen from Exotic Car Rental arrives in my lobby at 9:30, right on time. The contract is daunting (so many zeros!), but I agree to the terms, including overtime charges of $175 per hour. Reminding me that Exotic has already approved $10,000 on my Amex to cover the deductible, Alen asks me to sign a blank charge slip. (He'll fill it in later if I skin his $70,000 cat.) As I grip the pen, I feel my hand go numb.

The metallic-blue Jag, however, is an effective balm. "I'm sorry my car is more fabulous than yours," I mouth to strangers as I pilot the powerful car around town. At my hotel, the valet guys worship at my grille; as I drive past the Ivy restaurant at 5 mph (not one inch faster!), even the most self-important diners do a double take. Loving the attention, I decide to test one of Exotic's perks: I call them on the cell phone ($1.50 per minute) to say I can't unlock the emergency brake. "Where are you?" asks Robert, the owner. "I can be there in ten minutes."

For my third and final luxury jaunt, I can't resist Enterprise. The chain offers rock-bottom rates on fancy cars and tempts me with names like Jaguar, Mercedes, BMW, and Land Rover. And Enterprise is the only place in town that rents "exotic" cars without a stiff insurance requirement. A mere $21 a day buys full coverage for the vehicles, with no deductible. There is one major tradeoff: Unlike its haute competitors, Enterprise can't guarantee you a specific model.

Sunday morning, things get off to a dubious start. Enterprise is 40 minutes late picking me up; the BMW 525i I'd hoped to rent has been smashed the night before. All that's left in the "luxury" category is a dark green Land Rover Discovery for $99 a day (that's $36 less than Midway's rate). I sign the paperwork and am ready to relish the bargain. Then--$*%&!--another delay. "You're going to hate me, but we still have to fill the tank," says the woman behind the counter. When I finally get in, she explains the flashing red light on the dashboard is a "fakeout" alarm. (Later I discover it's quite real when it screams in protest as I open the back hatch.)

By now I'm feeling like a real Hollywood pro with all my automotive clout--until my celebrity sighting. The actor Hume Cronyn is standing in front of my hotel, waiting on the valet guys. Curious to see his chariot, I hang around. It's a spanking-new, shiny gold...Ford Taurus. As he drives away, I can feel all of my rented hubris disappear into the L.A. smogscape. I'll remember this moment next time I cruise the airport rental strip. And for that, I'm sure my boss will be grateful.