Speculation is building that electric car maker Tesla Motors could become an acquisition for a major Detroit automaker -- not just a tech company like Apple.

Veteran trader Yra Harris of Praxis Trading told CNBC this week that he predicts Tesla may be sold to General Motors in the coming year.

GM, like the other Big Three automakers, has had only limited success with electric vehicles. By the end of October, GM had sold less than 19,000 of its Chevy Volts, down almost 3% from last year. Ford sells fewer than 200 Ford Focus Electric vehicles each month. Both companies offer steep discounts to lure in buyers.

Would Tesla be a good fit for GM as Harris suggested? The luxury electric vehicle maker currently has a market capitalization of more than $18 billion, after shares rose more than 5% on Tuesday on news that its Model S had kept its five-star safety rating from the National Highway Traffic Safety Administration. A few reported engine fires in the Model S had spooked investors. The share price fell more than 20% from its peak back in September.

Tesla reported a record 5,500 Model S deliveries in its third quarter, as well as record production, a rising gross margin and expansion of its stores, service centers and charging stations. Per-share earnings have been better than consensus estimates in the past three quarters. But share trades at a hefty 100-plus times forward earnings.

Still, as Harris said, there would be no reason for GM to reinvent the wheel when it comes to electric vehicle technology. The Model S is critically acclaimed, while the Chevy Volt has had its own issues with car fires. But it all may come down to the valuation of Tesla — and whether CEO Elon Musk is ready to part with it and move on to his next project.

Tesla is happy to do things differently than other automakers, from the company-owned stores to the all-electric drivetrain. It also doesn't use union workers at its factory in Fremont, California (the former NUMMI plant, pictured). But now the United Auto Workers (UAW) is testing the waters for representation at the plant, according to a report in the San Francisco Chronicle.

UAW President Bob King has revealed that the UAW has created an organizing committee in Fremont. How this would change things at Tesla – and whether it would be a good or bad thing – is not really known, but it would certainly make the EV company more like the Big Three in this one aspect.

We heard rumblings of unions at Tesla in 2010, when Toyota and Tesla announced they were going to collaborate on developing EVs. At that time, the United Auto Workers said it wanted union workers back at the plant, especially some of the 4,500 who ended up unemployed after the General Motors/Toyota partnership that built cars at NUMMI was shut down. That didn't happen, but Tesla has called unionization a 'risk' to business in a financial report.

Tesla CEO Elon Musk at least has a plan for running his shop both with and without a union. As he told Wired in 2009, "Most of our experienced factory workers come from unionized environments, and we asked them what benefit did they see in unions. They said, 'Well, if their boss was an *******, they had recourse.' I said, 'Let's make a rule: There will be no *******s.' I fired someone for being an *******. And I only had to do that once, actually."

Tesla declined comment to AutoblogGreen about the new union rumblings, but when we spoke with Musk in 2012, he described the longer-than-average work hours:

Right now we're working six days a week. Some people are working seven days a week – I do – but for a lot of people, working seven days a week is not sustainable. The factory is operational seven days a week but most people we only ask to work six days a week right now and, obviously, we want to get that to a more reasonable number. I think people can sustain a 50-hour work week. I think that's a good work week. If you're joining Tesla, you're joining a company to work hard. We're not trying to sell you a bill of goods. If you can go work for another company and then maybe you can work a 40-hour work week. But if you work for Tesla, the minimum is really a 50-hour week and there are times when it'll be 60- to 80-hour weeks.

Despite the long hours, it's interesting to note that there do not seem to be calls from within Tesla for unionization.