Dakota Johnson & Giovanni Ribisi in 50 Shades of Carpooling

Dakota Johnson and Giovanni Ribisi might be a new couple ... or they might be extremely eco-conscious.

Giovanni and the "50 Shades of Grey" star both attended celeb jeweler Jennifer Meyer's 40th birthday bash Saturday night in WeHo. We don't know if they arrived together, but they definitely split in his ride.

No word if they're banging or just carpooling pals. If this is a friendzone sitch ... it's the first time we've seen them hanging out together.

They are both single -- Ribisi ended his second marriage to model Agyness Deyn in 2015, and Dakota split from her longtime bf last year.