Subaru has given STI enthusiasts a new mystery to ponder. The company filed trademarks for the names ACX and VPX, alongside their STI-badged counterparts ACX STI and VPX STI. This move is unusual for the brand, which typically favors full names like Forester, Outback, or Crosstrek, reserving alphanumeric codes for special cases such as BRZ and WRX.
What really grabs attention is the STI suffix. It instantly conjures images of sporty variants, race-bred technology, and sharper chassis tuning. But whether ACX and VPX will become production cars, concepts, special editions, or just defensive trademark registrations remains unknown.
The ACX badge has a historical precedent. Subaru showcased the ACX-II concept at the 1985 Tokyo Motor Show. That lineage later evolved into the XT and eventually the SVX, known domestically as the Alcyone. So ACX could theoretically point to a coupe—perhaps Alcyone Coupe eXperimental, though that’s still speculation. Still, the idea isn’t far-fetched.
In 2023, Subaru unveiled the Sport Mobility Concept, a large coupe bigger than the BRZ. In a market flooded with crossovers, launching a new coupe would be risky. But Honda’s return of the Prelude proves that niche, driver-focused models still have a pulse.
VPX is trickier. It lacks a clear link to Subaru’s history. It could refer to a different model, new technology, or a separate line of electrified sports cars. The X likely stands for eXperimental, as in WRX, but the other letters are cryptic.
Trademark filings alone don’t guarantee a production car. Automakers often register names as a precaution. Yet the simultaneous appearance of two STI-badged names is too intriguing to dismiss as coincidence.
Subaru has been missing a compelling sporting narrative outside the BRZ and WRX. ACX STI and VPX STI could be anything—concepts, future electric performance models, or something else. But one thing is already clear: the brand isn’t ready to abandon the idea of fast Subarus.