According to recent trademark filings.
EV buyers are eagerly awaiting delivery of the 2022 Rivian R1T, but the model has been repeatedly delayed until August at the earliest. Despite the delays, Rivian continues to receive multi-billion-dollar investments from partners like Ford and Amazon; Rivian is even building an electric delivery van for online commerce company. According to recent trademark filings, the Amazon van is not the only vehicle Rivian is currently working on.
Users on the Rivian Owners Forum spotted six new trademarks with the USPTO on July 23, 2021. Rivian recently applied to protect the names R3S, R4S, R5S, R3T, R4T, and R5T. The company announced plans to introduce six new models by 2025 back in 2019, so these might be the names for those vehicles.
Based on Rivian's existing naming scheme, the models with an "S" are SUVs, while the "T" models are pickup trucks. The Rivian R1S is already a fairly substantial SUV, but the R3S, R4S, and R5S names hint at even larger models. If larger, the R3T, R4T, and R5T could go stretch beyond half-ton truck territory, possibly entering into the heavy-duty segment.
These guesses are speculative, but it's hard to imagine Rivian creating a naming sequence where models shrink in size as the numbers grow bigger. With electric vehicles, smaller and lighter vehicles obviously achieve better range and efficiency, but larger vehicles have more space for battery cells.
There's no guarantee Rivian will use any of these names, as trademarks are often made preemptively to stop other companies from using them. Rivian previously trademarked R1V and R2X for an unspecified purpose and R2R for a rumored Subaru Outback-style model. We'd like to see Rivian start deliveries on its first two models, the R1T truck and R1S SUV before we start speculating on future models. Still, the company clearly wants to expand with a full model lineup, which sounds like an interesting prospect.