Austin Butler's still sounding like Elvis Presley two years after the movie's release, and it's just a part of him now ... so says supermodel Cindy Crawford.

Cindy -- whose daughter Kaia Gerber is in a relationship with the Golden Globe winner -- talked about Butler's learned Southern Twang during Wednesday night's "Watch What Happens Live With Andy Cohen" ... saying she had no idea the dude was from Anaheim!

Cindy says she thinks Austin spent so long mimicking Elvis, he absorbed the accent ... and, now it's just a part of him.

It's not weird for her though, Crawford adds  ... 'cause she didn't know AB before he took the role -- so, that's just who Austin is to her.

We told you all about Butler's lingering accent back in 2023 ... when his speech at the Golden Globes drew ire from people online -- slamming him for supposedly putting on a fake accent.

He defended himself during an interview on "The Graham Norton Show" ... saying people's comments made him self-conscious, but assuring everyone he wasn't faking it for attention.

His vocal coach later came out and called his accent "genuine" ... and may have the folksy twang for the rest of his life.

Seems like his vocal coach was on to something ... but, his possible future mother-in-law clearly doesn't mind.