Subaru has filed trademarks for both “ACX” and “ACX STI” in Australia, and the enthusiast internet is doing what it does best — building castles out of paperwork.
The filings were spotted by Australian outlet carsales, and while trademark applications are among the least reliable predictors of actual products, the STI suffix is doing a lot of heavy lifting here. Subaru hasn’t attached that badge to a globally available production car since the WRX STI exited stage left in 2021. Every STI appearance since has been a concept, a Japan-only special, or a limited-run exercise in nostalgia. A real, buyable STI model would be a genuine event.
The ACX name isn’t entirely new to Subaru’s history, though you’d be forgiven for drawing a blank. The ACX-II was a two-door concept shown at the 1985 Tokyo Motor Show, built on the XT platform with a 2.7-liter flat-six and full-time all-wheel drive. It was weird, angular, and deeply cool in the way only mid-’80s Japanese concepts could be.
What makes the current filing interesting is timing. Toyota has confirmed a new Celica is coming back, reportedly with a hybrid powertrain and AWD. Meanwhile, persistent rumors suggest Toyota may not partner with Subaru on the next-generation GR86, potentially leaving Subaru without a sports car dance partner for the first time in over a decade.
Those two threads point in different directions. One scenario has the ACX as Subaru’s purely in-house spiritual successor to the BRZ, a compact AWD coupe that leans into the brand’s core identity the way the BRZ leaned into lightweight rear-drive purity. The other scenario keeps the Toyota-Subaru relationship alive but reshapes it, with an AWD ACX sharing architecture with the new Celica. Both are plausible. Neither is confirmed.
Subaru’s 2023 Sport Mobility Concept offers a visual clue worth considering. That design married a two-door body with the brand’s increasingly rugged, squared-off design language — part sports car, part crossover in posture if not in ride height. It’s the kind of thing that could wear an ACX badge without looking out of place next to the Crosstrek and Forester.
But let’s be honest about the other possibility sitting in the room. Subaru has been on a naming spree with electric crossovers. An ACX could easily end up as another compact utility vehicle wearing a vaguely sporty name, with STI trim amounting to firmer dampers, bigger wheels, and a body kit. The auto industry has a long, inglorious history of strip-mining performance badges for marketing purposes.
The STI name still carries weight with a specific audience — the same people who remember rally stages, hood scoops, and boxer rumble. Whether Subaru intends to honor that legacy or simply borrow its equity is the real question these trademarks raise.
Trademark filings are cheap. Building the car people actually want is expensive. Subaru has the engineering DNA — symmetrical AWD, boxer engines, a motorsport pedigree that predates most of its current lineup. What it hasn’t demonstrated lately is the willingness to take a risk on something that isn’t a crossover.
Australia gets a lot of interesting trademark filings that never materialize into metal. This one, though, has enough context swirling around it — the Celica revival, the BRZ’s uncertain future, the STI void — to suggest something real might be brewing. Or it could be another crossover with a three-letter name. With Subaru, you place your bets and wait.
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