Detroit's big automakers are running out of time to avert a strike as tense contract talks with the United Auto Workers approach a critical deadline.

If there is no deal, as many as 150,000 UAW workers could go on strike against three automakers - Ford, General Motors and Stellantis, the parent company of Jeep and Chrysler - just after midnight on Friday, Sept. 15.

It has the potential to be the second largest work stoppage in 25 years, topped only by the SAG-AFTRA actors strike, which began last month. There are still many unknowns about how a strike would unfold and whether all 150,000 workers would walk off the job at once. But here is what we know at this point.

- - -

Why are the United Auto Workers threatening to strike?

The union and its 150,000 autoworkers are fighting for big pay and compensation improvements at the Big Three automakers. Under new UAW President Shawn Fain, the union is demanding a 40 percent wage increase over four years, shorter working hours and the restoration of many benefits that workers lost during contract negotiations around the time of the Great Recession in 2008. They say workers' wages haven't kept up with inflation, and they point to high executive pay and strong company profits as reasons they are due a big raise. Wages for full-timers at the Big Three currently range from roughly $18 an hour to $32 an hour, depending on seniority, according to the union. Starting wages are about $10 lower than what they would be had they kept up with inflation since 2007, the UAW says.

Autoworkers also say they are burned out from working mandatory overtime that for many can mean 50- or 60-hour workweeks. They are demanding to be paid for 40 hours a week but to work only 32 hours. And they want automakers to stop leaving so many workers in temporary status for years at a time, which deprives them of full wages and benefits.

The automakers have offered wage increases ranging from 9 percent to 14.5 percent over the life of a four-year contract but have balked at many of the other demands. The current contract ends Sept. 15 at midnight.

- - -

What would a strike do to car prices and availability?

Car prices have already soared in recent years beyond the reach of many Americans, due partly to covid-related component shortages that hobbled auto production for weeks at a time. A strike, particularly if it is short or limited to only certain factories, isn't likely to raise prices for most vehicles, analysts say. That's partly because there are plenty of non-UAW-produced vehicles on the market, including Teslas, Hondas, Toyotas and other brands. Also, dealers have some inventory stocked up of many UAW-produced models.

But some popular models that are already in relatively short supply, such as GM's Tahoe and Yukon SUVs, will become scarcer if a strike drags on, which could end up costing consumers more if dealers charge more than the sticker price, according to Pat Ryan, chief executive of CoPilot, a car-shopping app that tracks dealers' inventory and pricing. "Selection is going to get worse, prices are going to get higher if there is a strike, but it's going to be focused on the most popular brands and models. It's not going to be everywhere," Ryan said.

Ambrose Conroy, an auto expert and founder of Seraph Consulting, said he doesn't expect an immediate price increase. "We've seen big price increases and we have an affordability problem. I don't think a lot of the [manufacturers] have the room to increase more," he said.

- - -

How would a strike affect the economy?

The auto industry is vital to U.S. manufacturing, making up about 3 percent of gross domestic product. The UAW's 150,000 automotive members produce nearly half of the light vehicles manufactured in the United States, according to GlobalData.

Any strike, particularly if it drags on, will ripple out to affect suppliers and other businesses in auto-manufacturing communities. As auto factories shut down, they will stop ordering parts. Many auto-parts suppliers are still wounded from long shutdowns during the covid pandemic, and would be clobbered by another disruption, Conroy said. "They have not recovered the capital they need to survive a shutdown . . . if there is a three month shutdown, or even a one month, there are suppliers for which that might compromise their financial viability," he said.

Striking workers would stop receiving their regular paychecks and would have to get by on the $500 in strike pay the union would provide them each week. That would force many to cut back on spending, likely hurting restaurants, bars and other local businesses, said Michael Hicks, an economics professor at Ball State University.

Workers at auto dealerships would also suffer, losing commissions on sales of UAW-produced vehicles if they are in short supply, Hicks added.

- - -

What do the companies say about the contract negotiations and the possibility of a strike?

The Big Three say they are aiming to negotiate a fair contract with wage increases and benefits that they argue are more generous than most employers offer. So far, the raises the companies are offering range from 9 to 14.5 percent over the life of the four-year contract. They also note that their full-time workers receive compensation beyond their hourly wages, including profit-sharing payments and other bonuses. Over the past four years, amid high profits at the Big Three, profit-sharing checks have amounted to tens of thousands of dollars per full-time worker (temporary workers don't get them).

But the companies caution that they can't meet all of the UAW's demands and still remain competitive against non-unionized automakers such as Tesla, which has lower labor costs. Tesla has several years' head start on making EVs in large quantities and is already producing them profitably, while Ford and GM are still losing money on their EV production as they ramp up, said Dan Levy, an auto analyst at Barclays. Raising their labor costs would further widen their competitive gap with Tesla, he said.

The automakers have also balked at restoring some of the benefits that UAW workers lost around the time of the Great Recession, including defined-benefit pensions and company-financed health care in retirement. Instead of those pensions, workers hired after 2007 get 401(k) retirement accounts with a company contribution equaling 6.4 percent of workers' wages. They also get $1 per hour worked, or roughly $2,000 a year, paid into a 401(k) that they can use to purchase health care in retirement.

- - -

How might a strike unfold?

During the last UAW work stoppage in 2019, the union targeted GM only, holding a 40-day strike against the automaker until a new contract deal was reached. The UAW then used that deal to work out similar contracts with Ford and Stellantis. That's how contract bargaining and strikes often work - the union targets one company at a time.

This time, UAW President Shawn Fain has raised the specter of striking simultaneously against all three companies. He has said the UAW will strike against any company that hasn't reached a deal with the union by the time contracts expire at 11:59 p.m. on Sept. 14.

Analysts are skeptical that the union will walk off the job at every Big Three factory, noting that the UAW's $825 million strike fund would run out in under three months if all 150,000 autoworkers went on strike at once. Instead, some industry experts say that the union could target only the engine plants of the Big Three, which would effectively cripple vehicle production without requiring all workers to strike simultaneously.

That approach wouldn't necessarily allow nonstriking workers to carry on as usual, though. If the automakers don't have engines or other key components to produce vehicles, they could temporarily lay off workers throughout the system or cut their pay, said Levy, the automotive analyst at Barclays.