PHILADELPHIA – Forget great attendance and stellar customer service. Those are highly valued at Turn5, but what gets employees prime parking is driving to work in a Jeep Wrangler, a Ford Mustang or a few types of personal trucks.

Judging from the lineup in front of Turn5's headquarters outside Philadelphia on a recent afternoon, it's a popular perk, enhanced by the $2,000 the company gives employees to buy such wheels, plus $500 for parts.

The notion behind all that cash and pampering? That a company in business to serve auto enthusiasts should have employees in tune with that passion.

"Whoever knows about cars, we hire, specifically the cars we sell [parts] for," said Andrew Voudouris, 30, who with his older brother, Steve, 32, started Turn5 in 2003 in their parents' basement.

The company, which provides aftermarket parts primarily for Mustang, Wrangler and Ford F-150 vehicle models through three e-commerce sites, is now based in a 45,000-square-foot facility. But not for long. The sales niche is thriving so much that Turn5 — a take on racetrack terminology — will move this fall to premises twice as big. Its workforce is expected to grow from 425 to 1,000 in the next three years.

In the world of taillight tint inserts, axle-back exhausts, and an indulgence called a Jammock — a heavy-duty hammock designed for lounging when the top of a Jeep is removed — consumer passion for souping up vehicles is hot and expected to get hotter.

"I just don't see an end in sight," said Andrew Voudouris. He added that Turn5 has been profitable from the start with "double-digit" growth year over year, but declined to provide specific revenue. "People are so excited to buy. We're helping people with a hobby, not a commodity."

A study released earlier this year by San Francisco-based Grand View Research Inc. valued the global automotive aftermarket at $318.02 billion in 2015, projected to hit $486.36 billion by 2025. Hedges & Co., an Ohio market-research company serving the automotive aftermarket and motor-sports industries, has forecast online parts sales reaching $8.9 billion in 2017, up 16 percent from 2016.

Not that the Voudouris brothers were that prescient when, as high school students with an early appreciation for internet buying and selling, they used $2,000 in savings to start selling computer accessories online.

Their product line veered to car parts in 2004. Steve Voudouris had a 2001 Mustang and recognized that the aftermarket-parts field "was still very old school. People were still ordering out of catalogs, sending in cashier's checks," with delivery taking four to six weeks. He and Andrew "thought we could do this better."

They took their lead from online message boards, where aftermarket aficionados lamented not being able to see what a particular part looked like on a vehicle. Most catalogs showed them floating on a page.

The Voudouris brothers thought, "Let's solve that by using the car as 'the model,' " Andrew said. "It quickly evolved. If we can show people video and photography, it opens it up to more people."

Customer service is where the brothers think they can outdo their most formidable competitor, Amazon, believed to be the auto aftermarket's largest single online retailer.

"We're super-focused on how we create a better experience for our customers," Steve Voudouris said. "At the end of the day, that isn't something Amazon will be able to do."

Successful in the Mustang aftermarket through americanmuscle.com, they sought bank financing, only to be rejected despite "sales graphs going straight up," Steve said. "We've always bootstrapped the business. … It created really good discipline."

They ran the company from their parents' basement — expanding to four 20-by-20 tents and "a lot of tarps" in the yard to accommodate inventory — until 2007, when they moved into a warehouse. No more free rent.

"Once we moved there, we had to make money," Steve said.

The company started spending money on marketing and focused on Mustangs exclusively until 2013, selling car parts and producing a library of more than 2,000 videos demonstrating installation as well as the difference those parts make.

"Showing video for exhaust is huge, because what people care about is what it sounds like," Andrew said, leading a tour of Turn5's three recording studios, part of a complex that includes the headquarters and a 180,000-square-foot warehouse and call center. In March, Turn5 added a 40,000-square-foot distribution center in Las Vegas for faster satisfaction of orders from the West and Southwest. Last year, a 5,000-square-foot call center was added near Philadelphia.