The protesters are trying to escalate a movement targeting Tesla dealerships and vehicles in opposition to Musk's role as the head of the Trump administration's newly created Department of Government Efficiency, or DOGE.
Musk's team has gained access to sensitive data and shuttered entire agencies as he attempts to slash government spending.
Most of Musk's estimated $US340 billion ($A539 billion) fortune consists of the stock he holds in the electric vehicle company that he continues to run while also working alongside Trump.
Earlier protests have been somewhat sporadic.
Saturday marked the first attempt to surround all 277 of the automaker's showrooms and service centres in the US in hopes of deepening a recent decline in the company's sales.
By early afternoon, crowds ranging from a few dozen to hundreds of protesters had flocked to Tesla locations in New Jersey, Massachusetts, Connecticut, New York, Maryland, Minnesota and the automaker's home state of Texas.
Pictures posted on social media accounts showed protesters brandishing signs such as "Honk if you hate Elon" and "Fight the billionaire broligarchy."
The Tesla Takedown movement also hoped to rally protesters at more than 230 Tesla locations in other parts of the world.
Although the turnouts in Europe weren't as large as the crowds in the US, the anti-Musk sentiment was similar.
About two dozen protesters held signs lambasting Musk outside a Tesla dealership in London as passing cars and trucks tooted horns in support.
One of the signs displayed at the London protest showed a photo of Musk next to an image of Adolf Hitler making the Nazi salute — a gesture that Musk has been accused of reprising shortly after Trump's January 20 inauguration.
A person in a tyrannosaurus rex costume held another sign with a picture of Musk's straight-arm gesture that said, "You thought the Nazis were extinct. Don't buy a Swasticar".
"We just want to get loud, make noise, make people aware of the problems that we're facing," said Cam Whitten, an American who showed up at the London protest.
Some people opposed to Musk have gone beyond protests and set the automaker's vehicles on fire and committed other acts of vandalism that US Attorney General Pam Bondi has decried as domestic terrorism.
Musk indicated he was dumbfounded by the attacks during a March 20 company meeting and said the vandals should "stop acting psycho".
Crockett and other Tesla Takedown supporters have been stressing the importance for Saturday's protests to remain peaceful.
But police were investigating a fire that destroyed seven Tesla vehicles in northwestern Germany early Saturday morning.
It was wasn't immediately clear if the blaze, which was extinguished by firefighters, was related to the Tesla Takedown protests.
A growing number of consumers who bought Tesla vehicles before Musk took over DOGE have been looking to sell or trade in their cars while others have slapped on bumper stickers seeking to distance themselves from the billionaire's efforts to prune or shut down government agencies.
But Musk didn't appear concerned about an extended slump in sales of new Tesla cars in his March 20 address to employees.
He predicted Tesla will have sold more than 10 million cars worldwide by next year, up from about seven million cars now.
"There are times when there are rocky moments, where there is stormy weather, but what I am here to tell you is that the future is incredibly bright and exciting," Musk said.
After Trump was elected last November, investors initially saw Musk's alliance with the president as a positive development for Tesla and its long-running efforts to launch a network of self-driving cars.
That optimism helped lift Tesla's stock by 70 per cent in the period between Trump's November 5 election and his January 20 inauguration, creating an additional $US560 billion ($A888 billion) in shareholder wealth.
But virtually all those gains have evaporated amid investor worries about the Tesla backlash, lagging sales in the US, Europe and China, and Musk spending time overseeing DOGE.
"This continues to be a moment of truth for Musk to navigate this brand tornado crisis moment and get onto the other side of this dark chapter for Tesla," Wedbush Securities analyst Dan Ives said.
