Aurora Fr. Alfredo Juliano was a Roman Catholic priest who decided to build cars that were safer and in 1957 he presented his ideas in the form of the Aurora. Built on a Buick chassis, Aurora featured a plastic body designed to be dent and corrosion proof. The body also had cowcatcher like air-scoop in front and a foam-filled bumper designed to cushion a pedestrian who might be struck by the car. The car's bubble-like windshield was devised to enhance the driver's visibility -- because of its rain-shedding shape, wipers were not needed - and to provide more room between the glass and the driver or front-seat passenger's heads in a frontal impact. Not that their heads were likely to hit the windshield: The front seats were mounted on swivel; the concept was that if a frontal crash was imminent, occupants swing turn around and thus be protected by their seats. The car also had an internal roll cage, side-impact beams, a collapsible steering column, padded dashboard and seat belts. It was to be priced at $12,000. The prototype broke down repeatedly and had to be towed to its unveiling. The Aurora Motor Co. of Branford, Conn., funded in part by members of Juliano's congregation, went bankrupt after building the prototype and Juliano went to jail for accounting irregularities.

LAS VEGAS—On a summer Saturday morning, Jimmy Redmond drove his tangerine-colored lowrider with tinted windows into a gathering of classic automobiles, muscle cars and hotrods. As he popped open his Lamborghini-style doors skyward, Mr. Redmond dwarfed his ride: a 58.7-inch high, two-seat Smart car.

Mr. Redmond, a limo driver who often travels with a pet Chihuahua, says his tiny Smart car, made by Daimler AG's DAI.XE +0.06% Mercedes-Benz, doesn't get respect. On this day, a few muscle car drivers mock his ride as a "toy."

"I have a tiny car and a little 2-pound Chihuahua," says Mr. Redmond, 47 years old, who says he spent an additional $20,000 tricking out his $20,000 Smart car. "I tell them, 'I'm not compensating for anything.' "

Today, more people are choosing gas-saving, practical cars; the hybrid Toyota Motor Corp.'s 7203.TO -1.09% Prius was the best-selling car in California last year. But that doesn't stop drivers like Mr. Redmond from trying to put a little panache into being prudent, turning eco-friendly cars into lowriders, race cars and mini-monster trucks.

They are a far cry from more traditional souped-up rides. A Smart car is nine feet shorter than some classic Chevy Impalas and has five fewer cylinders. But even mockery from old-school hot-rod drivers hasn't fazed this new generation.

Many Prius "pimpers" have followed the lead of comedian Tommy Chong. He turned his hybrid into a black lowrider, with its body lowered to the ground, and added red and gray detailing and tinted windows in 2006. Mr. Chong, 75, who came to fame as half of the Cheech & Chong comedy duo, installed hydraulics to lift the car up and down, blacked out the taillights, and added a loud exhaust.

"I've always wanted a hot rod, so when I got the Prius I thought I gotta pimp this little guy out," says Mr. Chong.

Auto shops devoted to tricking out these types of cars are popping up in Southern California, the cradle of car culture that gave birth to lowriders. Hippy Motors in Los Angeles, which worked on Mr. Chong's Prius, specializes in making classic hot rods greener and eco-friendly cars friendlier on the eyes, according to Evan Singer, the proprietor.

Smart Madness in Signal Hill, Calif., focuses on turning Smart cars into sexier-looking cars. Customers can spend thousands on modifications such as throwing on larger tires or installing the Lamborghini-style doors, says Arthur Dominguez, a salesman at the shop.

Some drivers of traditional hot rods scoff at the trend.

At Cars and Coffee, the Saturday event in Las Vegas, Mr. Redmond arrived early with two other members of the Sin City Smarts, a group of Smart car owners that ride together. They scored prime parking spaces normally occupied by a contingent of Dodge muscle cars with large engines.

This meant that Debra Fortini—who drives a 2011 Dodge Challenger RT with the license plate "1SHEDVL"—and her comrades had to park in another row. "I was like, what is that? There's toys in my spot!'" says Ms. Fortini, a 39-year-old wearing a Pittsburgh Steelers cap.

Ms. Fortini says the modified Smarts are "cute" but "I like some real power."

Andres Siguenza, 33, who arrived in a cherry red 1964 Chevy Impala Super Sport convertible, a boat of a classic car, says he could put a Smart car in his trunk and "take it for a ride."

Mr. Redmond says he is used to the comments. One time, a crew of Chevy Camaro and Corvette drivers became angry after a similar parking spot incident, and began revving their engines and tossing insults.

"They look at these as like they're not real cars," sniffs Mr. Redmond. "We love our little cars. I wouldn't trade it for a big muscle car for anything."

Mr. Redmond's car is built for abuse. Protruding from the bumpers are silver "bumper spikes" that prevent trucks or people from literally pushing the approximately 1,800-pound car around. In the early days, Mr. Redmond says, there were tales of mischief makers engaging in "Smart tipping," similar to cow-tipping, though he never had his own car overturned.

Jeremy Cox, 26, who parked next to Mr. Redmond at Cars and Coffee, says that his friends call his bright green Smart car convertible a "pregnant roller skate." So Mr. Cox, who has spent about $20,000 modifying his car, exacted a small measure of revenge by installing a 195-decibel train horn.

"You don't expect it coming out of Smart car," says Mr. Cox, who proceeded to unleash a powerful blast, causing a nearby cluster of car enthusiasts to jump. "I don't really have any response when people say stuff—but I do have the horn."

The cars are flashy on the outside, but sometimes they also have some added oomph on the inside. Mr. Redmond installed a special air intake, exhaust and chip in the engine to boost the car's power to 86 horsepower from 71.

Charles Sohr, 41, whose black convertible Smart car is decorated with tattoo-like Ed Hardy designs, claims he is going to do an engine job that would bump it up to 300 horsepower. With one minor adjustment—removing a mechanism that limits the vehicle top's speed—Mr. Sohr says that he hit a top speed of 140 miles per hour while going downhill with a good tailwind.

A spokeswoman for Smart said "customer enthusiasm" is appreciated, but "any modifications" void the warranty.

These drivers share at least one thing with their muscle car brethren: aggrieved spouses. After Mr. Chong's wife complained about the bumpy ride in his Prius lowrider, he removed his hydraulic lift. And after a police officer gave him a ticket for the blacked out lights, he got rid of those too. Finally, he ditched the exhaust. "It had a real nice motorcycle sound, but it didn't go well with the electric sound I wanted," he says.

Mr. Redmond's wife has a nickname for his orange Smart car. "It's my husband's $40,000 clown car," says Heidi Redmond. "But he smiles every time he looks at it, so I guess it's worth it."

Write to Zusha Elinson at zusha.elinson@wsj.com