Guillermo Perez says he’s not a stereotypical Tesla owner. He isn’t an uber-rich guy who drives a quirky, high-tech car to impress his friends.

He’s a Chicago firefighter. And he says he worked hard to be able to buy his 2014 Tesla model S85, which cost just under $100,000 but, he figures, at least uses zero gas, so he would save there.

“I was pro-Tesla,” says Perez, who loved the idea of driving an American-made product that’s also environmentally friendly. “I literally threw my life savings into it.”

So he was pretty unhappy when a software update that the company pushed out in May to address a potential fire risk in some Tesla models ended up also cutting into how far he could drive without needing to recharge the battery pack and making the recharging process take longer.

After the May 15 update, Perez says the maximum range on his electric car suddenly fell from 255 miles to as few as 221 miles — a drop equivalent to the driving distance from downtown Chicago to Naperville.

The Northwest Side resident got in touch with Tesla.

“They said everything was fine,” Perez says. “I was, like, ‘Obviously not because I’m calling you.’ I thought it was odd — 30 miles right away.”

Perez is among more than two dozen Tesla owners who have filed complaints with the federal government about the change, which they say the company made to their cars without fully disclosing what the effects of that would be.

And a federal lawsuit filed in northern California in August seeks to include about 2,000 Tesla owners in a class-action case against the automaker. The suit, filed by attorney Edward C. Chen of Irvine, California, on behalf of lead plaintiff David Rasmussen, asks that all Tesla Model S and X cars be recalled and that Tesla owners be compensated either through a buyback or a battery-pack replacement, plus monetary damages.

Chen also has filed a petition with the National Highway Traffic Safety Administration, asking the federal agency to investigate the software updates and the potential fire risk.

His petition accuses Tesla of “using over-the-air software updates to mask and cover up a potentially widespread and dangerous issue with the batteries in their vehicles.”

Tesla company officials didn’t respond to several requests for comment.

Unlike a traditional gasoline-fueled car, the all-electric vehicles sold by Tesla since 2008 run on rechargeable lithium-ion batteries. Each car’s battery pack contains several thousand individual battery cells.

The cars are connected to the Internet and receive software updates much like a smartphone gets updates. Tesla owners are required to accept the software updates to keep their warranties active.

The car’s display screen shows the percentage of charge in the battery pack and indicates how many miles the car can go before recharging it.

That mileage can be affected by a number of factors — such as driving speed, how much weight the car carries, using the heat or air conditioning. But the number of miles displayed is supposed to give drivers a sense of how far they can still go — much like a gas gauge does for a conventional vehicle.

The batteries in question were offered with an eight-year, unlimited warranty that applies even to subsequent owners if the vehicle is sold.

NHTSA has received at least 25 complaints filed by Tesla owners in eight states that say the software update hurt their battery packs’ capacity.

Thousands of complaints and comments have been posted on a Tesla fan website.

Tesla brags that it has engineered “the safest car ever built” — a boast that U.S. regulators have cautioned is misleading.

In the past year, a handful of car fires have prompted concerns among Tesla owners.

First, a Tesla Model S caught fire in Los Angeles in June 2018 while its owner was sitting in traffic.

Then, in April, another Model S burst into flames while parked in a garage in Shanghai, China.

That was followed by a fire in San Francisco in May in which an unplugged Model S ignited while parked overnight in a residential garage.

Two weeks after the San Francisco fire, another Model S ignited in the garage of a shopping mall in Hong Kong. According to news accounts, the car was parked for about half an hour before the battery began to smoke and the car burst into flames.

As Tesla looked into the cause, it pushed out a software update May 15 to all Model S and X vehicles that the company said was being done “out of an abundance of caution.”

According to the lawsuit filed in California, the update notice that consumers were sent didn’t disclose that downloading it could affect the car’s mileage.

Rasmussen, the Victorville, California, plaintiff who is seeking class-action status for that lawsuit, so it would include other Tesla owners as well, says the effect of the update was immediate. He says his Model S’s range plummeted from about 247 miles to 217 miles.

Rasmussen says that 30-mile loss of range is significant, given his 125-mile one-way commute to work at a technology company. He says he’s used to stopping at a Tesla super-charging station but that now he has to do that more frequently, as well as having to wait longer for the battery pack to charge.

Perez, the Chicago firefighter, says the update sharply throttled his car’s charging ability. When he first got his car, he says, it took about an hour to fully charge it. Since the update, he says, it takes nearly twice as long.

“It would take forever to charge,” Perez says.

And planning road trips is now more complicated, according to Perez, who says he has to charge more frequently than he did before.

As a group, Tesla owners are known for their enthusiastic embrace of the brand. Loyal and often a little nerdy, they tend to rave about the technology and talk about how they enjoy supporting an environmentally friendly product.

In the early days, stories of positive customer interactions were common, with Tesla founder Elon Musk wowing fans by proclaiming his commitment to service and providing personal responses to them on Twitter.

That’s one reason why Rasmussen says he’s so disappointed. He says he supports addressing a potential fire risk but wonders, based on what he views as a lack of transparency on Tesla’s part, whether the fix will even be enough.

“I completely believe that there’s something defective in these batteries that should be covered under warranty,” he says. “Just tell us what’s going on.”

Perez agrees: “I’m still hopeful Tesla will change around and be back to the Tesla I used to know.”