William Hargrave couldn't believe his nose.

"It was just really overwhelming," the 25-year-old said of the smell enveloping the Uber he took to the airport. "I don't struggle with motion sickness, but I was feeling kind of car sick."

He looked up to find the culprit: tree-shaped air fresheners that reeked of cheap cologne. Seven of them.

Getting into an Uber or Lyft has become an assault on the nostrils. Drivers pack their cars with air fresheners-and not just the dangling kind.

There are puck-shaped cans that hide under seats and ones that clip to air-conditioner vents, blowing "Very Cherry" and "Hawaiian Aloha" into riders' faces. The back seat can be a special kind of hell in the cold of winter or on hot summer days, when windows are up and the only oxygen is scented.

Complaints have ratcheted up on social media, in petitions and through celebrity campaigns. So has the number of new scents. Cabs can now smell like Axe body spray, a Dunkin' latte or Downy fabric softener. Recent efforts to get drivers to tone it down haven't worked.

Hargrave, who works at a law firm in New Orleans, wanted to tell his driver that seven trees was overkill. But the Uber app only offered prewritten reviews. He picked the closest match: unpleasant smell.

"That man will probably see that and get an eighth tree," Hargrave said.

Jacque Keener got into an Uber this spring and saw it before he smelled it: a mix of red, blue and green trees tangled together to look like a large ball hanging from the rearview mirror.

Keener, who works in tech near Houston, estimated there were "north of 20, maybe 30" of them. He snapped pictures and texted his friends. "They just were all like, 'That is a crazy amount,'" he recalled.

The scent wasn't necessarily bad, just "aggressively fresh," he said. Keener, 27, put it a different way on social media: "It smells like I am developing new allergies."

Fragrances like air fresheners can trigger headaches, coughing or dizziness. To keep headaches and eye itchiness at bay, Katherine Sharpe now puts on an N95 mask before getting into an Uber or Lyft.

Two scents set her off the most: "Black Ice" from Little Trees-described by the company as a "mysteriously enticing cologne with notes of citrus and cedarwood," but which she finds indescribable. And the "Ocean Breeze" vent clip by Febreze that smells nothing like the ocean to her. "It's just this pungent artificial smell," said Sharpe, 33, a social-media manager from Washington, D.C.

The stench has a habit of sticking to her. Even her boyfriend can tell with just one sniff. "I go to give him a hug and he's like, 'Oh, you just took an Uber.'" She showers as soon as she gets home.

Riders have taken to social media to rant-"I felt like I was asphyxiated," one said on Reddit-and to call for the companies to offer a fragrance-free option or ban the fresheners altogether. "Please don't make your cars smell like a perfume store," a rider on X said.

One podcaster went straight to the top. "Can you add a filter for fragrance-free cars?" Mosheh Oinounou asked Uber Chief Executive Dara Khosrowshahi during a May episode of "Mo News."

"I'm sure we can work on it," said Khosrowshahi, who has led the company for nine years. "That's the first time I've heard that."

The exchange inspired TV personality Jenny McCarthy to start her own social-media campaign for fragrance-free Ubers, asking her millions of followers to share a video of her in the back seat of a car covering her nose with her shirt. "I'm not asking drivers to stop caring about how their cars smell," she said in an email. "I'm asking Uber to give passengers a choice."

Uber said it sends drivers instructions on keeping a scent-free car. "We'd rather riders remember the trip, not the air freshener," a spokesman said.

Lyft told its drivers in December to open windows or use odor absorbers instead of fragrances. The company also started offering its more expensive Extra Comfort as a fragrance-free option.

Sharpe said she tried it, only to find a tree in one and three in another. Lyft said customers can report on the app when an Extra Comfort ride falls short of its promises and receive a partial credit.

Drivers who use air fresheners are just trying to keep their cars smelling good between passengers, says Chris Gerace, who's been driving for Uber and Lyft for a decade. Riders emit all kinds of smells from the back seat: smoke, vomit, alcohol, strong perfumes. "Sometimes people fart," he said.

Gerace, who offers advice for drivers on the Rideshare Guy site, spritzes "Fresh Scent" Febreze after a passenger leaves and then drives around with the windows down. "A neutral smell is the best," he said, "because your nose is much different than my nose."

Drivers may not even realize how strong their air fresheners have gotten. Sit in a fog of fragrance long enough and your nose stops noticing.

Allison Anderman's breaking point was a slow-moving Lyft to Miami from the airport in Fort Lauderdale, Fla. The scent inside gave her a headache and made her nauseous.

"I told my husband when we got there, 'I'm not doing this again,'" said the 48-year-old from Philadelphia.

Anderman, who works in public policy, now calls a car service.

"I can't wait for Waymo," she said about the self-driving robotaxis, which aren't in her city yet. Her logic: A driverless car means no one to hang anything from the mirror.