Drive, they said

This is not the Mini.

Figures. The Mini Coopers, the sexy tarts of the PhillyCarShare fleet, typically end up down the Shore, or, like, the King of Prussia mall.

Some days at the beach, it seems every block, there's a seriously tan-challenged Philly dude and his girlfriend trying to find a parking space for their PhillyCarShare Mini.

But on this day, when the job is to experience a day in the life of a PhillyCarShare car - from the car's perspective - the chosen car is the sensible workhorse of the 500-strong fleet, the hybrid Toyota Prius.

And so, it's off to day care in West Philadelphia, the first of four separate adventures over 11 hours on this stifling hot Friday (air-conditioning, check). Meanwhile, the black Mini parked alongside at the 22d and South pod is going shopping at Neiman's.

The nonprofit PhillyCarShare experiment, started by five Penn grads six years ago, is a huge success, the largest regional car-sharing organization in the country. There are now 54,000 members, jockeying over 500 cars.

Aside from an occasional rogue member - one of whose whereabouts in an unauthorized Audi were being tracked last week, another seen smoking out the window of a Mini - and the always fluctuating cleanliness matrix ("Mad Dog Hair Everywhere!" one driver wrote in the meticulously chronicled damage diary of this Prius) - Philadelphia car-sharers are pretty much a happy bunch. And they know their fleet: Nobody who doesn't love the smell of a post-game boys hockey team will reserve the Honda Element at 12th and Walnut on a Saturday afternoon.

As for the cars, the Prius may not get the glamour trips, but they definitely get the cutest, cut-up kind of kids in the backseat (Yo, Dashiel and Gabriel, how is your "robotic family" doing? Haha).

In any case, for our Prius, the day begins with importance: a visit to a prospective day care in West Philadelphia, with 4-month-old Zoe Chen strapped in her seat in the back, mom Celine Chen, 37, alongside, dad Ken driving.

Celine and Ken are both Ph.D.s - Celine is a history professor at Penn, Ken is an unemployed economist - but they will not be the only highly educated passengers.

The PhillyCarShare experience appears to attract some impressive brainpower as its demographic, if not the most experienced drivers. (In the course of its day, the Prius will get stuck blocking traffic for an interminable seven minutes as driver Hayley Johnson, 25, navigates a tight turn from an alley onto a clogged street of double-parked cars outside the mosque at 45th and Walnut during Friday afternoon prayers, and, later, find itself backing up on the Schuylkill at 8:53 p.m. after driver Ben Frost, 26, missed the turnoff for 76 East and had a 9 p.m. deadline to return the car. The car, and its occupants, survived. And no late fee.)

Anyway, baby Zoe needs to get on the waiting list for the Penn Infant Center at 42d and Locust, her parents need to schmooze the director, and then they need to hit Whole Foods at 20th and Callowhill (a common PhillyCarShare stop, along with Ikea, which actually has designated PhillyCarShare parking) before returning the car at 12:15 p.m. sharp.

They pick the car up at 10 a.m. for their 10 a.m. appointment (they like to sleep in), and strap Zoe in. Everything goes smoothly until they cannot find the special malt drink that Celine wants for nursing, which necessitates an extra trip to Trader Joe's. From there, things get a little tense. Zoe is overdue for nursing, the car is a little hot from the sun, and the deadline is approaching. Ken has plotted out the trip with impressive precision (at least on the back end), but if you're going to get a $40 late fee for a $13 car-share trip, it defeats the point, especially if you're an unemployed economist. But no worries, some quick maneuvers, a dash into their house to drop off Mom and baby, and Chen arrives with a minute or two to spare.

From the quiet and efficient Chens, the Prius was supposed to take a somber turn: a trip to a hospital to pick up a patient. But that trip gets canceled at the last minute. Immediately sliding into that slot with a last-dash reservation is the goofy bantering trio of Hayley Johnson, 25, fiance Jay Wedge, 25, and third wheel Ben Marcus, 26, the guys recent law school grads at Penn, Hayley a liberal-arts grad student. They bring a welcome Seinfeld vibe to the Prius' day.

The three pals are frequent car-sharers together. Marcus does not drive, which makes him a PhillyCarShare moocher, a CarShareSharer. They've rented from 12:30 to 2:30 p.m., during which Wedge will drive himself to the airport, the Prius and Marcus idling while the couple linger over a goodbye kiss (Wedge even went ring shopping with Marcus in a PhillyCarShare car), and then Marcus and Johnson will, as promised, get lost on the way to pick up a package at the FedEx Home Delivery somewhere (who, even now, knows where?) near the airport. They will drop off the package at Marcus' apartment in West Philly and then head back to base camp.

Suffice to say, there's no GPS in PhillyCarShare cars and no pretest to see if you can handle the traffic jam of a Friday-afternoon mosque. "I'm only a Philly CarShare driver, not an everyday driver," Hayley notes, escaping scrape-free from that hairpin-sharp right turn. "It's just a Mercedes," she jokes about the car she is trying to squeeze past. "This is pretty tight."

Although two copies of the official "PhillyCarShare CD" are nonfunctional (one cracked, one splashed with some unknown substance), they find a home-burned CD, marked "Luma Guma," left behind in the car that plays some nice tunes. They resist the urge to take the CD. ("You can't," says Hayley. "It belongs to the car now.")

The Prius gets a rest, as its next occupant, nanny Kaviria Martinez, 37, doesn't really need the car until 3:30. Martinez and her employer, surgeon Jo Buyske, use PhillyCarShare as a second car, transporting just-turned-10 twins Dash and Gabe Buyske-Friedberg from tennis camp to the GameStop on Oregon Avenue to use birthday gift cards.

By this time, 4:18 p.m., as Martinez waits in the air-conditioned car outside the store for 30 minutes while the boys make their selections (they will pick the same game), the temperature is 97 degrees and the Prius has gone a total of 43.5 miles since 10 a.m.

At 4:49 p.m., they're ready to go, and, with impressive PhillyCarShare precision timing, Martinez gets the car back by its 5 p.m. deadline.

The Prius gets a dinner break until 7:15 p.m. - taking your PhillyCarShare car out during rush hour does not seem to be a proposition that tempts many members. At that time, Ben Frost, 26, the finance coordinator for Drexel's graduate business school, will come along.

For a brief moment, it looks like the Prius might have scored the coveted Shore trip - cool temps, ocean breeze, open windows, here we come! - as the Prius heads over the Ben Franklin Bridge toward Jersey.

But no, its destination is the more prosaic Cherry Hill Mall to check out the sale at Abercrombie. And, after the death-defying missed-exit correction on the Schuylkill, the boathouses laughing off in the distance, it's back at 22d and South by 9 p.m. Total mileage for the day: 67.9.

And naturally, there's no sign of the Mini.