The team-up has led to a flurry of announcements on the partnership's objective, including joint EV tech development, a new factory in the USA and a whole host of juicy product details.
Well, sort of, and it could be a long way off.
Mazda, whose sales are an eighth that of Toyota, says it lacks the funds to develop electric cars on its own.
Toyota may be the king of hybrid tech but neither brand has really got to grips with full EV cars with much enthusiasm.
The sheer cost of the plant also makes a partnership logical, as it boosts cost-efficiency and economies of scale.
Meanwhile, Mazda, which has developed its original fuel-saving technology, has been behind in the field of electric vehicles.
A capital tie-up with Mazda would be the latest addition to Toyota's sprawling empire, which includes Japanese truck maker Hino Motors and minicar maker Daihatsu Motor Co.
Grand jury subpoenas issued in relation to Trump Jr., Russian lawyer meeting
Coons added: "Ensuring that the special counsel can not be removed improperly is critical to the integrity of his investigation". Mueller was appointed as special counsel in May following the firing of James Comey as Federal Bureau of Investigation director.
According to Reuters, Mazda, who has sales are one eighth of Toyota's, only has a research budget of 140 billion yen per year - compared to Toyota's one trillion yen. The company will start manufacturing cars in 2021 and is expected to provide employment to about 4,000 people.
The US plant will have the capacity to produce approximately 300,000 vehicles a year and create up to 4,000 jobs. The automakers plan to produce Toyota Corollas and a new Mazda SUV crossover at the new plant.
Mazda said that "nothing has been decided yet" and that the company "will have a board meeting on this matter today". American consumers are buying that model in record numbers, while Mazda also is seeing booming demand for its entry in that segment, the CX-5.
"A great investment in American manufacturing!" he tweeted Friday morning.
Trump had previously criticized Toyota for taking auto production and jobs to Mexico. The value of the shares mutually acquired by both companies will be equivalent.
The two will take small stakes in each other as part of the tie-up: Toyota, the world's second-largest automaker by vehicle sales a year ago, will take a five per cent share of Mazda.
This alliance doesn't mean that both brands are now symbiotic.