Last year, Toyota and Mazda announced plans to build a new $1.6 billion production plant in Alabama as part of a joint partnership between the two automakers, which will build up to 300,000 vehicles annually. Originally, Toyota intended to build Corollas for the US at the plant, while Mazda was expected to work on an upcoming crossover.

These plans have now changed, however, as Toyota has announced it will be using the plant to build a new, yet-to-be announced SUV. Toyota says the change was made in response to "changing market demands and a growing consumer appetite for light trucks and SUVs which are achieving record sales.", including Toyota's best-selling RAV4. Production of the Corolla will continue at Toyota's Blue Springs, Mississippi, plant.

Toyota added that more details about the future SUV will be released at a later date. Mazda's plan to build a new SUV has not changed, however. Speaking to Car and Driver, Toyota and Mazda representatives confirmed the two SUVs will share components and suppliers but emphasized that both SUVs will be two entirely different vehicles that will be "developed independently by each brand." Production of Toyota's SUV is expected to begin in 2021.

So what could Toyota's mystery new SUV be? A production version of the off-road-focused Toyota FT-4X Concept seems like a real possibility. Toyota previously said it's considering making a successor to the rugged FJ Cruiser to rival the Jeep Wrangler, which hasn't been in production since 2014. Toyota Motor North America CEO Jim Lentz admitted "there's room for an authentic small off-road SUV" and that an FJ Cruiser successor would be inspired by the FT-4X and FT-AC concepts if it got the green light for production. Presumably, it would slot below the 4Runner and Land Cruiser.

Unveiled at the 2017 New York Auto Show, the Toyota FT-4X concept has a rugged appearance with tow hooks in the bumpers, tie-down points in the roof rack and power supply points for exterior lights. No powertrain details were revealed, but Toyota said at the time it envisioned the off-roader with a small four-cylinder engine and mechanical four-wheel-drive system.